VOL-2727: Only attempt to add tcont/gem if its actually new

When adding the tcont or gem to the handler
pon cache return true or false if its actually unique
and added to the cache.  This prevents the tp task
from adding potentially the same alloc id to a different
tcont id

Also remove unused code.

Change-Id: Iee1b7698c84b0790c624fe67c32b6ea215c8eab5
2 files changed