scsi: sd: sd_zbc: Rename sd_zbc_setup_write_cmnd

Rename sd_zbc_setup_write_cmnd() to sd_zbc_write_lock_zone() to be clear
about what the function actually does. To be consistent, also rename
sd_zbc_cancel_write_cmnd() to sd_zbc_write_unlock_zone().

No functional change is introduced by this patch.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>