block: remove typo in kernel-doc of set_disk_ro()

Commit 52f019d4 ("block: add a hard-readonly flag to struct gendisk")
provides some kernel-doc for set_disk_ro(), but introduces a small typo.

Hence, make htmldocs warns on ./block/genhd.c:1441:

  warning: Function parameter or member 'read_only' not described in 'set_disk_ro'
  warning: Excess function parameter 'ready_only' description in 'set_disk_ro'

Remove that typo in the kernel-doc for set_disk_ro().
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/genhd.c

@@ -1431,7 +1431,7 @@ static void set_disk_ro_uevent(struct gendisk *gd, int ro)
 /**
  * set_disk_ro - set a gendisk read-only
  * @disk:	gendisk to operate on
- * @ready_only:	%true to set the disk read-only, %false set the disk read/write
+ * @read_only:	%true to set the disk read-only, %false set the disk read/write
  *
  * This function is used to indicate whether a given disk device should have its
  * read-only flag set. set_disk_ro() is typically used by device drivers to