bluetooth: btnxpuart: Support for controller wakeup gpio config

When using the out-of-band WAKE_IN and WAKE_OUT pins, we have to tell
the firmware which pins to use (from controller point of view). This
allows to report remote wakeup support when WAKE_OUT(c2h) is configured.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Neeraj Sanjay Kale <neeraj.sanjaykale@nxp.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>