dm raid1: remove impossible mempool_alloc error test

mempool_alloc can't fail if __GFP_WAIT is specified, so the condition
that tests if read_record is non-NULL is always true.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/dm-raid1.c

@@ -1195,11 +1195,9 @@ static int mirror_map(struct dm_target *ti, struct bio *bio,
 		return -EIO;
 
 	read_record = mempool_alloc(ms->read_record_pool, GFP_NOIO);
-	if (likely(read_record)) {
 	dm_bio_record(&read_record->details, bio);
 	map_context->ptr = read_record;
 	read_record->m = m;
-	}
 
 	map_bio(m, bio);