msm: netfilter: NATTYPE Refresh Timer Changes

NATTYPE entry timeout will not be updated when packets
start flowing through IPA and eventually can timeout.
Make changes to refresh the NATTYPE entry timeout from
the connection tracking netlink module which is used by
IPANAT to update conntrack timeout. Also make the timeout
dynamic by taking the expiry timeout value from connection
tracking entry. Otherwise NATTYPE entry will not timeout
even when all the corresponding conntrack entries expire.

CRs-FIXED: 490813
Change-Id: Ibb225d7b91070ca9948c7a11f0b5925a8435915c
Signed-off-by: Tyler Wear <twear@codeaurora.org>