block: Fix partition check for host-aware zoned block devices

Commit a33df75c ("block: use an xarray for disk->part_tbl") modified
the method to check partition existence in host-aware zoned block
devices from disk_has_partitions() helper function call to empty check
of xarray disk->part_tbl. However, disk->part_tbl always has single
entry for disk->part0 and never becomes empty. This resulted in the
host-aware zoned devices always judged to have partitions, and it made
the sysfs queue/zoned attribute to be "none" instead of "host-aware"
regardless of partition existence in the devices.

This also caused DEBUG_LOCKS_WARN_ON(lock->magic != lock) for
sdkp->rev_mutex in scsi layer when the kernel detects host-aware zoned
device. Since block layer handled the host-aware zoned devices as non-
zoned devices, scsi layer did not have chance to initialize the mutex
for zone revalidation. Therefore, the warning was triggered.

To fix the issues, call the helper function disk_has_partitions() in
place of disk->p...