nds32: Fix the allmodconfig build. To make sure CONFIG_CPU_LITTLE_ENDIAN is default y

This way we can build kernel with CONFIG_CPU_LITTLE_ENDIAN=y. Build allmodconfig
and allnoconfig are available too. It also fixes the endian mismatch issue
because AFLAGS and LDFLAGS is not passed correctly.
Signed-off-by: Vincent Ren-Wei Chen <vincentc@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>

arch/nds32/Kconfig.cpu

 comment "Processor Features"
 
 config CPU_BIG_ENDIAN
-	bool "Big endian"
+	def_bool !CPU_LITTLE_ENDIAN
 
 config CPU_LITTLE_ENDIAN
-        def_bool !CPU_BIG_ENDIAN
+	bool "Little endian"
+	default y
 
 config HWZOL
 	bool "hardware zero overhead loop support"

arch/nds32/Makefile

@@ -32,8 +32,12 @@ endif
 
 ifdef CONFIG_CPU_LITTLE_ENDIAN
 KBUILD_CFLAGS   += $(call cc-option, -EL)
+KBUILD_AFLAGS   += $(call cc-option, -EL)
+LDFLAGS         += $(call cc-option, -EL)
 else
 KBUILD_CFLAGS   += $(call cc-option, -EB)
+KBUILD_AFLAGS   += $(call cc-option, -EB)
+LDFLAGS         += $(call cc-option, -EB)
 endif
 
 boot := arch/nds32/boot