Add xdriver_xf86-video-udlfb
The Linux kernel has two drivers for use by DisplayLink USB monitors
The udlfb framebuffer driver to be used with xdriver_xf86-video-udlfb
The udl KMS driver to be used with xserver_xorg-server provided modesetting

Signed-off-by: Xerxes Rånby <xerxes@gudinna.com>