Add support for SMSC UFX6000/7000 USB display adapters

This patch adds framebuffer suport for SMSC's UFX6000 (USB 2.0) and
UFX7000 (USB 3.0) display adapters.

Signed-off-by: Steve Glendinning <steve.glendinning@smsc.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>