btrfs: call submit_bio_hook directly in submit_one_bio

BTRFS has 2 inode types (for the purposes of the code in submit_one_bio)
- ordinary data inodes (including the freespace inode) and the btree
inode. Both of these implement submit_bio_hook so btrfsic_submit_bio can
never be called from submit_one_bio so just remove it.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -168,11 +168,8 @@ int __must_check submit_one_bio(struct bio *bio, int mirror_num,
 
 	bio->bi_private = NULL;
 
-	if (tree->ops)
-		ret = tree->ops->submit_bio_hook(tree->private_data, bio,
-						 mirror_num, bio_flags);
-	else
-		btrfsic_submit_bio(bio);
+	ret = tree->ops->submit_bio_hook(tree->private_data, bio, mirror_num,
+					 bio_flags);
 
 	return blk_status_to_errno(ret);
 }