brcmfmac: Disable powersave mode for P2P link.

For p2p client mode powersave mode should be kept disabled. It is
working but inefficient. In general p2p links do no benefit from this
mode, because these links are setup temporarily to transfer data.

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>