Use simple dict update and dict literal to optimize code
Use simple dict update and dict literal to optimize code

A couple of filters dictionary merge used hacking way, not sound logic
and poor readability. Replaced them with dictionary update functions.

Replaced dict function with dict literal to keep consistency with rest
of the code.

Change-Id: If5aa37c87ef9b0eb9101ca6e52bf370d358a0857

openstack/networking-sfc,openstack/networking-sfc