dm integrity: don't check null pointer before kvfree and vfree

The functions kfree, vfree and kvfree do nothing if we pass a NULL
pointer to them.  So we don't need to test the pointer for NULL.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-integrity.c

@@ -3548,9 +3548,7 @@ static void dm_integrity_dtr(struct dm_target *ti)
 		destroy_workqueue(ic->writer_wq);
 	if (ic->recalc_wq)
 		destroy_workqueue(ic->recalc_wq);
-	if (ic->recalc_buffer)
 	vfree(ic->recalc_buffer);
-	if (ic->recalc_tags)
 	kvfree(ic->recalc_tags);
 	if (ic->bufio)
 		dm_bufio_client_destroy(ic->bufio);