The current code uses integer literals to index
btrfs_space_info->block_groups[] array. Instead use corresponding
enums from 'enum btrfs_raid_types'.
Signed-off-by: chandan <chandan@linux.vnet.ibm.com> Reviewed-by: David Sterba <dsterba@suse.cz> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>