drivers/block/xen-blkback/common.h: Fix spelling typo in comment

Fix spelling typo in comment.
Reported-by: k2ci <kernel-bot@kylinos.cn>
Signed-off-by: liyouhong <liyouhong@kylinos.cn>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20231226095701.172080-1-liyouhong@kylinos.cnSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/xen-blkback/common.h

@@ -132,7 +132,7 @@ struct blkif_x86_32_request {
 struct blkif_x86_64_request_rw {
 	uint8_t        nr_segments;  /* number of segments                   */
 	blkif_vdev_t   handle;       /* only for read/write requests         */
-	uint32_t       _pad1;        /* offsetof(blkif_reqest..,u.rw.id)==8  */
+	uint32_t       _pad1;        /* offsetof(blkif_request..,u.rw.id)==8 */
 	uint64_t       id;
 	blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
 	struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];