zbd: Cleanup zbd_init()

zbd: Cleanup zbd_init()

For a job using a zoned device, the zonesize option must always specify
the device zone size. That is checked in the function parse_zone_info().
The zonesize checks in zbd_init() apply only to jobs running with
zonemode=zbd on a regular block device. So move these checks into
init_zone_info() which is used to emulate zone information for regular
block devices.

Fix t/zbd test #43 accordingly.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>