Bluetooth: btrtl: add support for the RTL8723CS

The Realtek RTL8723CS is a SDIO WiFi chip. It also contains a Bluetooth
module which is connected via UART to the host.

It shares lmp subversion with 8703B, so Realtek's userspace
initialization tool (rtk_hciattach) differentiates varieties of RTL8723CS
(CG, VF, XX) with RTL8703B using vendor's command to read chip type.

Also this chip declares support for some features it doesn't support
so add a quirk to indicate that these features are broken.

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Bastian Germann <bage@debian.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>