wil6210: add wil_netif_rx() helper function

Move common part of wil_netif_rx_any into new helper function and
add support for non-gro receive using netif_rx_ni.

Change-Id: I4d45e89effdad0cd01776c6cfca792c880accc44
Signed-off-by: Dedy Lansky <dlansky@codeaurora.org>