qcow2: Fix documentation of get_cluster_table()

This function has not been returning the offset of the L2 table since
commit 3948d1d

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: b498733b6706a859a03678d74ecbd26aeba129aa.1517840876.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

block/qcow2-cluster.c

@@ -647,8 +647,7 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
  * for a given disk offset, load (and allocate if needed)
  * the l2 table.
  *
- * the l2 table offset in the qcow2 file and the cluster index
- * in the l2 table are given to the caller.
+ * the cluster index in the l2 table is given to the caller.
  *
  * Returns 0 on success, -errno in failure case
  */