null_blk: Fix description of the fua parameter

The description of the fua module parameter is defined using
MODULE_PARM_DESC() with the first argument passed being "zoned". That is
the wrong name, obviously. Fix that by using the correct "fua" parameter
name so that "modinfo null_blk" displays correct information.

Fixes: f4f84586 ("null_blk: Introduce fua attribute")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20240702073234.206458-1-dlemoal@kernel.org


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