A platform device can be used to provide some specific resources in
order to manage the controller. In this first patch we retrieve the
reset gpio which is used to power on/off the controller.

The main issue is to match the current tty with the correct pdev.
In case of ACPI, we can easily find the right tty/pdev pair because
they are both child of the same UART port.

If controller is powered-on from the driver, we need to wait for a
HCI boot event before being able to send any command.
Signed-off-by: Loic Poulain <loic.poulain@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>