lib: proportions.c trivial sparse lock annotation

Suppresses sparse warning:
lib/proportions.c:159:16: warning: context imbalance in 'prop_get_global': wrong count at exit
lib/proportions.c:159:16:    context 'RCU': wanted 0, got 1
lib/proportions.c:164:2: warning: context imbalance in 'prop_put_global': unexpected unlock
lib/proportions.c:164:2:    context 'RCU': wanted 0, got -1

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/proportions.c

@@ -147,6 +147,7 @@ void prop_change_shift(struct prop_descriptor *pd, int shift)
  * this is used to track the active references.
  */
 static struct prop_global *prop_get_global(struct prop_descriptor *pd)
+__acquires(RCU)
 {
 	int index;
 
@@ -160,6 +161,7 @@ static struct prop_global *prop_get_global(struct prop_descriptor *pd)
 }
 
 static void prop_put_global(struct prop_descriptor *pd, struct prop_global *pg)
+__releases(RCU)
 {
 	rcu_read_unlock();
 }