ARM: keystone: enable big endian support

Keystone code is big endian compatible,
so mark it as one that supports big endian.

Note this patch just allows to select Big endian build
for ARCH_KEYSTONE, but it does not enable BE by default.
Signed-off-by: NTaras Kondratiuk <taras.kondratiuk@linaro.org>
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>

arch/arm/mach-keystone/Kconfig

@@ -11,6 +11,7 @@ config ARCH_KEYSTONE
 	select ARM_ERRATA_798181 if SMP
 	select COMMON_CLK_KEYSTONE
 	select TI_EDMA
+	select ARCH_SUPPORTS_BIG_ENDIAN
 	help
 	  Support for boards based on the Texas Instruments Keystone family of
 	  SoCs.