[XFS] Fix sparse warning in kmem_shake_allow

We can't return a masked result of a __bitwise type. Compare it to 0 first
to keep the behaviour without the warning.

SGI-PV: 968555
SGI-Modid: xfs-linux-melb:xfs-kern:29309a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>

fs/xfs/linux-2.6/kmem.h

@@ -103,7 +103,7 @@ extern void *kmem_zone_zalloc(kmem_zone_t *, unsigned int __nocast);
 static inline int
 kmem_shake_allow(gfp_t gfp_mask)
 {
-	return (gfp_mask & __GFP_WAIT);
+	return (gfp_mask & __GFP_WAIT) != 0;
 }
 
 #endif /* __XFS_SUPPORT_KMEM_H__ */