brcmfmac: remove brcmf_proto_hdrpull() from bus interface

The use of the function brcmf_proto_hdrpull() is moved to the
common part of the driver and consequently it can be removed
from the bus interface.

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>