writeback: fix call of incorrect macro

 the variable 'history' is of type u16, it may be an error
 that the hweight32 macro was used for it
 I guess macro hweight16 should be used

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 2a81490 ("writeback: implement foreign cgroup inode detection")
Signed-off-by: Maxim Korotkov <korotkov.maxim.s@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230119104443.3002-1-korotkov.maxim.s@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: ProjectMutilation

fs/fs-writeback.c

@@ -829,7 +829,7 @@ void wbc_detach_inode(struct writeback_control *wbc)
 		 * is okay.  The main goal is avoiding keeping an inode on
 		 * the wrong wb for an extended period of time.
 		 */
-		if (hweight32(history) > WB_FRN_HIST_THR_SLOTS)
+		if (hweight16(history) > WB_FRN_HIST_THR_SLOTS)
 			inode_switch_wbs(inode, max_id);
 	}