Add csq-cs908 tvbox fex file

The CSQ CS908 is an A31s based top-set box, with 1G RAM, 8G NAND,
rtl8188etv usb wifi, 2 USB A receptacles (1 connected through the OTG
controller), ethernet, 3.5 mm jack with a/v out and hdmi out:

http://www.geekbuying.com/item/CS908-Allwinner-A31S-Quad-Core-1-2GHz-Android-4-4-Mini-TV-Box-HDMI-HDD-Player-1G-8G-WIFI-Miracast---Black-333395.html

Note it has no sdcard slot!

Signed-off-by: Hans de Goede <hdegoede@redhat.com>