msm: ipa: support qmap control pkt using pkt_init

Currently the qmap control pkts are sent back to AP
from modem because of exception. The fix is
to use pkt_init to skip filtering/natting on IPA-HW to
reach modem instead. Also there is a requirement for
AP-side to send back qmap flow control acks immediately
after receiving the requets. The code change is to make
2st level high-watermark for those qmap control pkts to
not be dropped. Also rmnet_ipa driver won't stop queue
if the current pkt is qmap control pkt even when
outstanding pkts above the first level of
high-watermark.

Change-Id: I3074e4a37d74c491593e109c1df0c99da85a5e57
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>