btrfs: abort transaction on error in btrfs_remove_block_group()

btrfs: abort transaction on error in btrfs_remove_block_group()

When btrfs_remove_block_group() fails we abort the transaction in its
single caller (btrfs_remove_chunk()). This makes it harder to find out
where exactly the failure happened, as several steps inside
btrfs_remove_block_group() can fail.

So make btrfs_remove_block_group() abort the transaction whenever an
error happens, instead of aborting in its caller.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>