msm: ipa: enhancements to L2TP over UDP

When L2TP over UDP tunnelling is used, add provision to filter
out based on next header in case if specific packets like
ICMPv6 packets need to be routed to apps.

Change-Id: I48076cc0fa5fcf5476761b3cbf78d5235a6b2b79
Signed-off-by: Chaitanya Pratapa <cpratapa@codeaurora.org>