tridentfb: improved register values on TGUI 9680

Improved values for some registers after Xorg Trident driver.  The main
problem was that values set by BIOS have been ignored.

This patch completely remove random pixels ("snow") on the TGUI 9680 and
9440 (not supported yet by the driver).  It does not help with the "snow"
on 3DImage and Blade3D cards.

There is also small improvement in timing calculations (hblank start and
vblank start)

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/video/trident.h b/include/video/trident.h
index 51ec5a9..fa690b9 100644
--- a/include/video/trident.h
+++ b/include/video/trident.h
@@ -25,6 +25,7 @@
 #define CYBER9520	0x9520
 #define CYBER9525DVD	0x9525
 #define TGUI9660	0x9660
+#define PROVIDIA9685	0x9685
 #define IMAGE975	0x9750
 #define IMAGE985	0x9850
 #define BLADE3D		0x9880