Bluetooth: btbcm: Stop using upper nibble of rev to chose between uart/USB paths

btbcm_setup_patchram() was using the upper nibble of the revision code to
determine if we are dealing with an uart or USB connected bcm-bt device,
but just as btbcm_initialize() has started accepting 1 and 2 as uart
connected devices, I've now encountered an USB connected device (0a5c:216c)
which has 0 in the upper nibble. So it seems that the upper nibble is not
really a reliable indicator of the bus type.

Instead check hdev->bus which does give us a reliable indication. This
fixes the patchram code trying to load the patchram by the fallback BCM.hcd
filename, now it correctly requests BCM43142A0-0a5c-216c.hcd.

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