Remove unused methods from cinder.utils

These methods were left over from the split from Nova and are unused still.

Remove methods:
	is_valid_ipv4()
	make_dev_path()
	convert_to_list_dict()
	partition_dict()
	subset_dict()

Change-Id: Icb36aa6a2d1f607c440a2d524d3480de23d1cb7a
Merge "Remove unused methods from cinder.utils"