Bluetooth: hci_bcm: Move platform_get_irq call to bcm_probe

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

Most of the code in bcm_platform_probe is actually not platform
specific and will work with any struct device passed to it, the one
platform specific call in bcm_platform_probe is platform_get_irq.

This commit moves platform_get_irq call to the platform-driver's bcm_probe
function, 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>