btrfs: zoned: refine extent allocator hint selection

The hint block group selection in the extent allocator is wrong in the
first place, as it can select the dedicated data relocation block group for
the normal data allocation.

Since we separated the normal data space_info and the data relocation
space_info, we can easily identify a block group is for data relocation or
not. Do not choose it for the normal data allocation.

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