zbd: simplify zbd_close_zone()

Change the interface of zbd_close_zone() to directly use a pointer to a
zone information structure as all callers already have this information.
Also do nothing for zones that are not marked as open instead of
figuring out this fact by searching the array of open zones.

No functional changes.

Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com>
Link: https://lore.kernel.org/r/20211214012413.464798-8-damien.lemoal@opensource.wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>