brcmfmac: revise handling events in receive path

Move event handling out of brcmf_netif_rx() avoiding the need
to pass a flag. This flag is only ever true for USB hosts as
other interface use separate brcmf_rx_event() function.

Reviewed-by: Hante Meuleman <hante.meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>
Reviewed-by: Franky Lin <franky.lin@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>