mm/zsmalloc: add missing annotation for unpin_tag()

Sparse reports a warning at unpin_tag()()

warning: context imbalance in unpin_tag() - unexpected unlock

The root cause is the missing annotation at unpin_tag()
Add the missing __releases(bitlock) annotation

Signed-off-by: Jules Irenge <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

mm/zsmalloc.c

@@ -896,7 +896,7 @@ static void pin_tag(unsigned long handle) __acquires(bitlock)
 	bit_spin_lock(HANDLE_PIN_BIT, (unsigned long *)handle);
 }
 
-static void unpin_tag(unsigned long handle)
+static void unpin_tag(unsigned long handle) __releases(bitlock)
 {
 	bit_spin_unlock(HANDLE_PIN_BIT, (unsigned long *)handle);
 }