btrfs: add space_info parameter for block group creation

Add struct btrfs_space_info parameter to btrfs_make_block_group(), its
related functions and related struct. Passed space_info will have a new
block group.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>