Makefile: Fix KERNEL_ARCH for big endian ARC

Big endian ARC is called arceb, not arcbe.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

Makefile

@@ -239,7 +239,7 @@ ARCH:=$(call qstrip,$(BR2_ARCH))
 KERNEL_ARCH:=$(shell echo "$(ARCH)" | sed -e "s/-.*//" \
 	-e s/i.86/i386/ -e s/sun4u/sparc64/ \
 	-e s/arcle/arc/ \
-	-e s/arcbe/arc/ \
+	-e s/arceb/arc/ \
 	-e s/arm.*/arm/ -e s/sa110/arm/ \
 	-e s/aarch64/arm64/ \
 	-e s/bfin/blackfin/ \