Btrfs: Remove code duplication in comp_keys

comp_keys is duplicating what is done in btrfs_comp_cpu_keys, so just
call it.
Signed-off-by: NDiego Calleja <diegocg@gmail.com>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

fs/btrfs/ctree.c

@@ -557,19 +557,7 @@ static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 
 	btrfs_disk_key_to_cpu(&k1, disk);
 
-	if (k1.objectid > k2->objectid)
-		return 1;
-	if (k1.objectid < k2->objectid)
-		return -1;
-	if (k1.type > k2->type)
-		return 1;
-	if (k1.type < k2->type)
-		return -1;
-	if (k1.offset > k2->offset)
-		return 1;
-	if (k1.offset < k2->offset)
-		return -1;
-	return 0;
+	return btrfs_comp_cpu_keys(&k1, k2);
 }
 
 /*