dt-bindings: net: bluetooth: nxp: Add wakeup pin properties

NXP bluetooth controller may have GPIO pins used and routed for `WAKE_IN`
and `WAKE_OUT`, such pin info must be known so that the driver is can
configure the controller's firmware accordingly.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>