brcmfmac: remove rx helper function from bus interface

The bus interface provided a wrapper function to pass a single
packet to the common driver part filling a skb queue with one
packet. For clarity the caller now sets up the skb queue and
call the rx bus interface function.

Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>