ARM: mach-imx: clk-busy: Staticize clk_busy_mux_ops

Fix the following sparse warning:

arch/arm/mach-imx/clk-busy.c:150:16: warning: symbol 'clk_busy_mux_ops' was not declared. Should it be static?
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/mach-imx/clk-busy.c

@@ -147,7 +147,7 @@ static int clk_busy_mux_set_parent(struct clk_hw *hw, u8 index)
 	return ret;
 }
 
-struct clk_ops clk_busy_mux_ops = {
+static struct clk_ops clk_busy_mux_ops = {
 	.get_parent = clk_busy_mux_get_parent,
 	.set_parent = clk_busy_mux_set_parent,
 };