Bluetooth: Remove trailing whitespaces from Kconfig

Fixed a coding style issue. Removed trailing whitespaces in
drivers/bluetooth/Kconfig.
Signed-off-by: Stephan Gabert <stephan.gabert@fau.de>
Signed-off-by: Nicolas Pfeiffer <nicolas.pfeiffer@fau.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>