arc: Move SYS_LITTLE_ENDIAN / SYS_BIG_ENDIAN selection to Kconfig

We can determine which of these we need given CPU_BIG_ENDIAN being
enabled or not, so move that logic to Kconfig from config.mk.

Cc: Alexey Brodkin <alexey.brodkin@synopsys.com>
Cc: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/Kconfig b/arch/Kconfig
index 6495e78..c4dc47d 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -53,6 +53,8 @@
 	select SUPPORT_OF_CONTROL
 	select SYS_CACHE_SHIFT_7
 	select TIMER
+	select SYS_BIG_ENDIAN if CPU_BIG_ENDIAN
+	select SYS_LITTLE_ENDIAN if !CPU_BIG_ENDIAN
 
 config ARM
 	bool "ARM architecture"