brcmfmac: removed dhd_proto.h.

dhd_proto.h was cleaned up and prototypes were moved to dhd.h.
dhd_proto.h was removed. This is a step in cleaning and
restucturing protocol layer.

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