Btrfs: Fix printk and variable name

Correct spelling typo in btrfs.
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

fs/btrfs/ctree.h

@@ -413,7 +413,7 @@ struct btrfs_root_backup {
 	__le64 bytes_used;
 	__le64 num_devices;
 	/* future */
-	__le64 unsed_64[4];
+	__le64 unused_64[4];
 
 	u8 tree_root_level;
 	u8 chunk_root_level;

fs/btrfs/volumes.c

@@ -4294,7 +4294,7 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
 
 			rcu_read_lock();
 			name = rcu_dereference(dev->name);
-			pr_debug("btrfs_map_bio: rw %d, secor=%llu, dev=%lu "
+			pr_debug("btrfs_map_bio: rw %d, sector=%llu, dev=%lu "
 				 "(%s id %llu), size=%u\n", rw,
 				 (u64)bio->bi_sector, (u_long)dev->bdev->bd_dev,
 				 name->str, dev->devid, bio->bi_size);