mm: fix up sparse warning in gfpflags_allow_blocking

sparse says:

    include/linux/gfp.h:274:26: warning: incorrect type in return expression (different base types)
    include/linux/gfp.h:274:26:    expected bool
    include/linux/gfp.h:274:26:    got restricted gfp_t

...add a forced cast to silence the warning.

Signed-off-by: Jeff Layton <[email protected]>
Cc: Mel Gorman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

include/linux/gfp.h

@@ -271,7 +271,7 @@ static inline int gfpflags_to_migratetype(const gfp_t gfp_flags)
 
 static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
 {
-	return gfp_flags & __GFP_DIRECT_RECLAIM;
+	return (bool __force)(gfp_flags & __GFP_DIRECT_RECLAIM);
 }
 
 #ifdef CONFIG_HIGHMEM