dm space map metadata: fix missing store of apply_bops() return value

In commit 6096d91a ("dm space map metadata: fix occasional leak
of a metadata block on resize"), we refactor the commit logic to a new
function 'apply_bops'.  But when that logic was replaced in out() the
return value was not stored.  This may lead out() returning a wrong
value to the caller.

Fixes: 6096d91a ("dm space map metadata: fix occasional leak of a metadata block on resize")
Cc: stable@vger.kernel.org
Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/persistent-data/dm-space-map-metadata.c

@@ -249,7 +249,7 @@ static int out(struct sm_metadata *smm)
 	}
 
 	if (smm->recursion_count == 1)
-		apply_bops(smm);
+		r = apply_bops(smm);
 
 	smm->recursion_count--;