zsmalloc: Delete an unnecessary check before the function call "iput"

iput() tests whether its argument is NULL and then returns immediately.
Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.

Link: http://lkml.kernel.org/r/559cf499-4a01-25f9-c87f-24d906626a57@users.sourceforge.net
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/zsmalloc.c

@@ -2174,8 +2174,7 @@ static int zs_register_migration(struct zs_pool *pool)
 static void zs_unregister_migration(struct zs_pool *pool)
 {
 	flush_work(&pool->free_work);
-	if (pool->inode)
-		iput(pool->inode);
+	iput(pool->inode);
 }
 
 /*