block: uapi: fix comment about block device ioctl

Fix the comment mentioning ioctl command range used for zoned block
devices to reflect the range of commands actually implemented.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Link: https://lore.kernel.org/r/20210509234806.3000-1-damien.lemoal@wdc.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>