block: add zone write plug condition to debugfs zone_wplugs

block: add zone write plug condition to debugfs zone_wplugs

Modify queue_zone_wplug_show() to include the condition of a zone write
plug to the zone_wplugs debugfs attribute of a zoned block device.
To improve readability and ease of use, rather than the zone condition
raw value, the zone condition name is given using blk_zone_cond_str().

Suggested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>