package/x11r7/xdriver_xf86-video-sis: bump version

Use git snapshot for compatibility with xorg xserver 1.17.0,
remove patches applied upstream.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>