dm writecache: advance the number of arguments when reporting max_age

When reporting the "max_age" value the number of arguments must
advance by two.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: 3923d48 ("dm writecache: implement gradual cleanup")
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-writecache.c

@@ -2479,6 +2479,8 @@ static void writecache_status(struct dm_target *ti, status_type_t type,
 			extra_args += 2;
 		if (wc->autocommit_time_set)
 			extra_args += 2;
+		if (wc->max_age != MAX_AGE_UNSPECIFIED)
+			extra_args += 2;
 		if (wc->cleaner)
 			extra_args++;
 		if (wc->writeback_fua_set)