msm: rndis_ipa: use netif_rx_ni to push packets to network stack

rndis_ipa indicates packets to the network stack in process
context so netif_rx_ni is the correct API to use. Using
netif_rx in this context can cause fluctuations in latency
of NET_RX being serviced.

Change-Id: I1f8105a85b601819d4e015910520d2851a762b3b
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>