lib/lockref: __lockref_is_dead can be boolean

Make __lockref_is_dead return bool due to this function only using either
true or false as its return value.

No functional change.

Link: http://lkml.kernel.org/r/1513266622-15860-3-git-send-email-baiyaowei@cmss.chinamobile.com
Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/lockref.h

@@ -44,7 +44,7 @@ extern void lockref_mark_dead(struct lockref *);
 extern int lockref_get_not_dead(struct lockref *);
 
 /* Must be called under spinlock for reliable results */
-static inline int __lockref_is_dead(const struct lockref *l)
+static inline bool __lockref_is_dead(const struct lockref *l)
 {
 	return ((int)l->count < 0);
 }