The ACPI subsys is going to move over to instantiating ACPI enumerated
HCIs as serdevs, rather then as platform devices.

This means that the serdev driver paths of hci_bcm.c also need to start
supporting (runtime)pm through GPIOs and a host-wake IRQ.

The hci_bcm code is already mostly independent of how the HCI gets
instantiated, but even though the code only cares about pdev->dev, it
was storing pdev itself in struct bcm_device.

This commit stores pdev->dev rather then pdev in struct bcm_device, this
is a preparation patch for adding (runtime)pm support to the serdev path.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>