ppc: Fix compile error in arch/ppc/lib/strcase.c

Now that the strncasecmp implementation takes a size_t third parameter,
we need to get a definition of size_t from somewhere.
Signed-off-by: NPaul Mackerras <paulus@samba.org>

arch/ppc/lib/strcase.c

 #include <linux/ctype.h>
+#include <linux/types.h>
 
 int strcasecmp(const char *s1, const char *s2)
 {