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.

Signed-off-by: Dedy Lansky <dlansky@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>