[Bluetooth] Fix firmware loading problem of BT3C driver

Before the PCMCIA subsystem was fully integrated into the device and
driver model, the BT3C driver had to workaround this when loading the
firmware. This workaround is broken and makes the driver oops when
loading the firmware. This patch removes this workaround and uses now
the provided device structure from the PCMCIA subsystem.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>