c6x: pass endianness info to sparse

c6x depends on the macro '_BIG_ENDIAN' being defined or not
to correctly select or define endian-specific macros, structures
or pieces of code.

This macro is predefined by the compiler but sparse knows nothing
about it and thus may pre-process files differently from what
gcc would.

Fix this by passing '-D_BIG_ENDIAN' when compiling a big-endian
kernel, like GCC would have done.

To: Mark Salter <msalter@redhat.com>
To: Aurelien Jacquiot <a-jacquiot@ti.com>
CC: linux-c6x-dev@linux-c6x.org
Signed-off-by: NLuc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: NMark Salter <msalter@redhat.com>

arch/c6x/Makefile

@@ -25,6 +25,7 @@ KBUILD_AFLAGS   += -mbig-endian
 LINKFLAGS       += -mbig-endian
 KBUILD_LDFLAGS  += -mbig-endian
 LDFLAGS += -EB
+CHECKFLAGS	+= -D_BIG_ENDIAN
 endif
 
 head-y          := arch/c6x/kernel/head.o