Bluetooth: btrtl: Create separate module for Realtek BT driver

As already done for btintel and btbcm export setup as separate function
in a vendor-specific module to hold all the Realtek specific commands.

Signed-off-by: Carlo Caione <carlo@endlessm.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

diff --cc drivers/bluetooth/Kconfig
Simple merge

diff --cc drivers/bluetooth/Makefile
Simple merge

diff --cc drivers/bluetooth/btrtl.c
Simple merge

diff --cc drivers/bluetooth/btrtl.h
Simple merge

diff --cc drivers/bluetooth/btusb.c
Simple merge