netfilter: Port Trigger: Support added for Port Trigger Feature

With Port Trigger feature, the DL traffic forward ports get opened
once the UL traffic is sent on respective trigger ports.

Change-Id: I7fc67a48ab4d079aa3e7c1b5fa81b4611f54493f
Acked-by: Vinisha Varre <vvarre@qti.qualcomm.com>
Signed-off-by: Paras Jain <parassin@codeaurora.org>