[MIPS] There is no __GNUC_MAJOR__

Gcc major version number is in __GNUC__. As side effect fix checking
with sparse if sparse was built with gcc 4.1 and mips cross-compiler
is 3.4.

Sparse will inherit version 4.1, __GNUC__ won't be filtered from
"-dM -E -xc" output, sparse will pick only new major, effectively becoming
gcc version 3.1 which is unsupported.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/Makefile

@@ -623,7 +623,7 @@ LDFLAGS			+= -m $(ld-emul)
 
 ifdef CONFIG_MIPS
 CHECKFLAGS += $(shell $(CC) $(CFLAGS) -dM -E -xc /dev/null | \
-	egrep -vw '__GNUC_(MAJOR|MINOR|PATCHLEVEL)__' | \
+	egrep -vw '__GNUC_(|MINOR_|PATCHLEVEL_)_' | \
 	sed -e 's/^\#define /-D/' -e "s/ /='/" -e "s/$$/'/")
 ifdef CONFIG_64BIT
 CHECKFLAGS		+= -m64