brcmfmac: Add multi channel support for P2P.

Multi channel support was disabled. This patch will enable it and
configure the P2P GO on the correct frequency when multi channel
is used.

Reviewed-by: Arend Van Spriel <arend@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>