dm: fix spelling errors

Fixed some confusing spelling errors that were currently identified,
the details are as follows:

-in the code comments:
        dm-cache-target.c: 1371:        exclussive      ==> exclusive
        dm-raid.c: 2522:                repective       ==> respective

Signed-off-by: Shen Lichuan <shenlichuan@vivo.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

drivers/md/dm-cache-target.c

@@ -1368,7 +1368,7 @@ static void mg_copy(struct work_struct *ws)
 			 */
 			bool rb = bio_detain_shared(mg->cache, mg->op->oblock, mg->overwrite_bio);
 
-			BUG_ON(rb); /* An exclussive lock must _not_ be held for this block */
+			BUG_ON(rb); /* An exclusive lock must _not_ be held for this block */
 			mg->overwrite_bio = NULL;
 			inc_io_migrations(mg->cache);
 			mg_full_copy(ws);

drivers/md/dm-raid.c

@@ -2519,7 +2519,7 @@ static int super_validate(struct raid_set *rs, struct md_rdev *rdev)
 		rdev->saved_raid_disk = rdev->raid_disk;
 	}
 
-	/* Reshape support -> restore repective data offsets */
+	/* Reshape support -> restore respective data offsets */
 	rdev->data_offset = le64_to_cpu(sb->data_offset);
 	rdev->new_data_offset = le64_to_cpu(sb->new_data_offset);