scsi: sd_zbc: Fix potential memory leak

Rework sd_zbc_check_zone_size() to avoid a memory leak due to an early
return if sd_zbc_report_zones() fails.

Reported-by: David.butterfield <david.butterfield@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Cc: stable@vger.kernel.org
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>