Change capabilities filters to use resource type

A recent change in scheduler/filters/capabilities_filters.py added log
message, however since this filter is supposed to accommodate both Nova
and Cinder capabilities, the 'instance_type' should be 'resource_type'.

Change-Id: I21ccd7b628009aaf5db4af896b64b73fb6c40fe0
Merge "Change capabilities filters to use resource type"