Blackfin: fix strncmp.o build error

Fix some more fallout of the string changes:

  CC      arch/blackfin/lib/strncmp.o
In file included from include/linux/bitmap.h:9,
                 from include/linux/nodemask.h:90,
                 from include/linux/mmzone.h:17,
                 from include/linux/gfp.h:5,
                 from include/linux/kmod.h:23,
                 from include/linux/module.h:14,
                 from arch/blackfin/lib/strncmp.c:14:
include/linux/string.h: In function ‘strstarts’:
include/linux/string.h:132: error: implicit declaration of function ‘strncmp’
make[1]: *** [arch/blackfin/lib/strncmp.o] Error 1

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
CC: Rusty Russell <rusty@rustcorp.com.au>

arch/blackfin/lib/strncmp.c

@@ -8,9 +8,8 @@
 
 #define strncmp __inline_strncmp
 #include <asm/string.h>
-#undef strncmp
-
 #include <linux/module.h>
+#undef strncmp
 
 int strncmp(const char *cs, const char *ct, size_t count)
 {