btrfs: Factor out common extent locking code in submit_compressed_extents
Irrespective of whether the compress code fell back to uncompressed or
a compressed extent has to be submitted, the extent range is always
locked. So factor out the common lock_extent call at the beginning of
the loop. No functional changes just removes one duplicate lock_extent
call.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>