arm: omap2: Fix compiler warning

Fix build warning in arch/arm/mach-omap2/emif-common.c and
arch/arm/mach-omap2/omap4/emif.c with gcc 7.3.0:

  warning: duplicate 'const' declaration specifier [-Wduplicate-decl-specifier]
Signed-off-by: NBin Meng <bmeng.cn@gmail.com>
Reviewed-by: NTom Rini <trini@konsulko.com>

arch/arm/mach-omap2/emif-common.c

@@ -599,7 +599,7 @@ s8 addressing_table_index(u8 type, u8 density, u8 width)
  * tables of the device using DDR clock frequency
  */
 static const struct lpddr2_ac_timings *get_timings_table(const struct
-			lpddr2_ac_timings const *const *device_timings,
+			lpddr2_ac_timings *const *device_timings,
 			u32 freq)
 {
 	u32 i, temp, freq_nearest;

arch/arm/mach-omap2/omap4/emif.c

@@ -90,8 +90,7 @@ static const struct lpddr2_min_tck min_tck_jedec = {
 	.tFAW = 8
 };
 
-static const struct lpddr2_ac_timings const*
-			jedec_ac_timings[MAX_NUM_SPEEDBINS] = {
+static const struct lpddr2_ac_timings *jedec_ac_timings[MAX_NUM_SPEEDBINS] = {
 	&timings_jedec_200_mhz,
 	&timings_jedec_400_mhz
 };