Bluetooth: btbcm: Fold Patch loading + applying into btbcm_initialize()

Instead of having btbcm_initialize() fill a passed in fw_name buffer
and then have its callers use that to request the firmware + load
it into the HCI, make btbcm_initialize() do this itself the first
time it is called (its get called a second time to reset the HCI
after the firmware has been loaded).

This removes some code duplication and makes it easier for further
patches in this series to try more then 1 firmware filename.

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