btrfs: remove stale comment for argument seed of btrfs_find_device

Commit b2598edf ("btrfs: remove unused argument seed from
btrfs_find_device") removed the argument seed from btrfs_find_device
but forgot the comment, so remove it.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Su Yue <l@damenly.su>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -6670,8 +6670,6 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
  *
  * If devid and uuid are both specified, the match must be exact, otherwise
  * only devid is used.
- *
- * If @seed is true, traverse through the seed devices.
  */
 struct btrfs_device *btrfs_find_device(struct btrfs_fs_devices *fs_devices,
 				       u64 devid, u8 *uuid, u8 *fsid)