btrfs: zoned: directly call do_zone_finish() from btrfs_zone_finish_endio_workfn()

When btrfs_zone_finish_endio_workfn() is calling btrfs_zone_finish_endio()
it already has a pointer to the block group. Furthermore
btrfs_zone_finish_endio() does additional checks if the block group can be
finished or not.

But in the context of btrfs_zone_finish_endio_workfn() only the actual
call to do_zone_finish() is of interest, as the skipping condition when
there is still room to allocate from the block group cannot be checked.

Directly call do_zone_finish() on the block group.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>