clk: meson: mpll: correct N2 maximum value

Gxbb datasheet says N2 maximum value is 127 but the register field is
9 bits wide, the maximum value should 511.

Test shows value greater than 127, all the way to 511, works well
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Link: lkml.kernel.org/r/20170309104154.28295-9-jbrunet@baylibre.com

drivers/clk/meson/clk-mpll.c

@@ -68,7 +68,7 @@
 #define SDM_MIN 1
 #define SDM_MAX 16383
 #define N2_MIN	4
-#define N2_MAX	127
+#define N2_MAX	511
 
 #define to_meson_clk_mpll(_hw) container_of(_hw, struct meson_clk_mpll, hw)