fix gfp_t annotations for slub

Since we have use like ~SLUB_DMA, we ought to have the type
set right in both cases.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/slub_def.h

@@ -160,7 +160,7 @@ static inline struct kmem_cache *kmalloc_slab(size_t size)
 #define SLUB_DMA __GFP_DMA
 #else
 /* Disable DMA functionality */
-#define SLUB_DMA 0
+#define SLUB_DMA (__force gfp_t)0
 #endif
 
 void *kmem_cache_alloc(struct kmem_cache *, gfp_t);