powerpc/sparse: Pass endianness to sparse

Explicitly give sparse an endianness in the Makefile, so that it
doesn't get confused.

Normally we have #ifdef one and #else the other, so it doesn't usually
matter, but we have been bitten by it before, and indeed this patch
fixes a number of sparse errors.
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/Makefile

@@ -181,6 +181,11 @@ KBUILD_CFLAGS	+= -pipe -Iarch/$(ARCH) $(CFLAGS-y)
 CPP		= $(CC) -E $(KBUILD_CFLAGS)
 
 CHECKFLAGS	+= -m$(CONFIG_WORD_SIZE) -D__powerpc__ -D__powerpc$(CONFIG_WORD_SIZE)__
+ifdef CONFIG_CPU_BIG_ENDIAN
+CHECKFLAGS	+= -D__BIG_ENDIAN__
+else
+CHECKFLAGS	+= -D__LITTLE_ENDIAN__
+endif
 
 KBUILD_LDFLAGS_MODULE += arch/powerpc/lib/crtsavres.o