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 <[e-mail]>
Signed-off-by: Daniel Axtens <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/Makefile

···
 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