clk: imx: make mux parent strings const

As the commit 2893c379 ("clk: make strings in parent name arrays
const"), let's make the parent strings const, otherwise we may meet
the following warning when compiling:

drivers/clk/imx/clk-imx7ulp.c: In function 'imx7ulp_clocks_init':
drivers/clk/imx/clk-imx7ulp.c:73:35: warning: passing argument 5 of
	'imx_clk_mux_flags' discards 'const' qualifier from pointer target type

  clks[IMX7ULP_CLK_APLL_PRE_SEL] = imx_clk_mux_flags("apll_pre_sel", base + 0x508, 0,
	1, pll_pre_sels, ARRAY_SIZE(pll_pre_sels), CLK_SET_PARENT_GATE);
                                   ^
In file included from drivers/clk/imx/clk-imx7ulp.c:23:0:
drivers/clk/imx/clk.h:200:27: note: expected 'const char **' but argument is
 of type 'const char * const*'
...

Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/imx/clk-busy.c

@@ -154,7 +154,7 @@ static const struct clk_ops clk_busy_mux_ops = {
 
 struct clk *imx_clk_busy_mux(const char *name, void __iomem *reg, u8 shift,
 			     u8 width, void __iomem *busy_reg, u8 busy_shift,
-			     const char **parent_names, int num_parents)
+			     const char * const *parent_names, int num_parents)
 {
 	struct clk_busy_mux *busy;
 	struct clk *clk;

drivers/clk/imx/clk-fixup-mux.c

@@ -70,7 +70,7 @@ static const struct clk_ops clk_fixup_mux_ops = {
 };
 
 struct clk *imx_clk_fixup_mux(const char *name, void __iomem *reg,
-			      u8 shift, u8 width, const char **parents,
+			      u8 shift, u8 width, const char * const *parents,
 			      int num_parents, void (*fixup)(u32 *val))
 {
 	struct clk_fixup_mux *fixup_mux;

drivers/clk/imx/clk.h

@@ -69,7 +69,7 @@ struct clk *imx_clk_busy_divider(const char *name, const char *parent_name,
 
 struct clk *imx_clk_busy_mux(const char *name, void __iomem *reg, u8 shift,
 			     u8 width, void __iomem *busy_reg, u8 busy_shift,
-			     const char **parent_names, int num_parents);
+			     const char * const *parent_names, int num_parents);
 
 struct clk_hw *imx7ulp_clk_composite(const char *name,
 				     const char * const *parent_names,
@@ -82,7 +82,7 @@ struct clk *imx_clk_fixup_divider(const char *name, const char *parent,
 				  void (*fixup)(u32 *val));
 
 struct clk *imx_clk_fixup_mux(const char *name, void __iomem *reg,
-			      u8 shift, u8 width, const char **parents,
+			      u8 shift, u8 width, const char * const *parents,
 			      int num_parents, void (*fixup)(u32 *val));
 
 static inline struct clk *imx_clk_fixed(const char *name, int rate)
@@ -91,7 +91,8 @@ static inline struct clk *imx_clk_fixed(const char *name, int rate)
 }
 
 static inline struct clk *imx_clk_mux_ldb(const char *name, void __iomem *reg,
-		u8 shift, u8 width, const char **parents, int num_parents)
+			u8 shift, u8 width, const char * const *parents,
+			int num_parents)
 {
 	return clk_register_mux(NULL, name, parents, num_parents,
 			CLK_SET_RATE_NO_REPARENT | CLK_SET_RATE_PARENT, reg,
@@ -211,7 +212,8 @@ static inline struct clk *imx_clk_gate4(const char *name, const char *parent,
 }
 
 static inline struct clk *imx_clk_mux(const char *name, void __iomem *reg,
-		u8 shift, u8 width, const char **parents, int num_parents)
+			u8 shift, u8 width, const char * const *parents,
+			int num_parents)
 {
 	return clk_register_mux(NULL, name, parents, num_parents,
 			CLK_SET_RATE_NO_REPARENT, reg, shift,
@@ -219,7 +221,8 @@ static inline struct clk *imx_clk_mux(const char *name, void __iomem *reg,
 }
 
 static inline struct clk *imx_clk_mux2(const char *name, void __iomem *reg,
-		u8 shift, u8 width, const char **parents, int num_parents)
+			u8 shift, u8 width, const char * const *parents,
+			int num_parents)
 {
 	return clk_register_mux(NULL, name, parents, num_parents,
 			CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE,
@@ -227,8 +230,9 @@ static inline struct clk *imx_clk_mux2(const char *name, void __iomem *reg,
 }
 
 static inline struct clk *imx_clk_mux_flags(const char *name,
-		void __iomem *reg, u8 shift, u8 width, const char **parents,
-		int num_parents, unsigned long flags)
+			void __iomem *reg, u8 shift, u8 width,
+			const char * const *parents, int num_parents,
+			unsigned long flags)
 {
 	return clk_register_mux(NULL, name, parents, num_parents,
 			flags | CLK_SET_RATE_NO_REPARENT, reg, shift, width, 0,