Bluetooth: hci_bcm: Add (runtime)pm support to the serdev driver

Make the serdev driver use struct bcm_device as its driver data and share
all the pm / GPIO / IRQ related code paths with the platform driver.

After this commit the 2 drivers are in essence the same and the serdev
driver interface can be used for all ACPI enumerated HCI UARTs.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>