Trivial: Remove doc for non-existing param in format_dict().

There is no parameter named format.

Change-Id: I286006430efb2850b978b6f2abaed87216156d12

Author: tang-chen

openstackclient/common/utils.py

@@ -145,7 +145,6 @@ def format_dict(data):
     """Return a formatted string of key value pairs
 
     :param data: a dict
-    :param format: optional formatting hints
     :rtype: a string formatted to key='value'
     """