Remove objectify decorator from dbapi.update_* methods

This patch removes the objectify decorator from the update_chassis,
update_port and update_node dbapi's methods. The problem with the
objectify decorator is that dbapi methods doesn't get the context,
so when forming the RPC object using the decorator we can't store the
context within the object (which is what we want to do to have consistent
object interfaces).

Also there are no parts of the code that is expecting the returned RPC
object from the dbapi.update_*() methods so we can just simply get ride
of the decorator.

Partial-Bug: 1314732
Change-Id: Ib5ac15100214b351607e1c17aa663fa4c123bc7a
Merge "Remove objectify decorator from dbapi.update_* methods"