Broken struct

@see this commit - xorg/xserver@5a945f54

It remmoved maxHValue and maxVValue from struct _ScrnInfoRec in the xf86str.h include file. The primary driver file in this repo, tseng_drivers.c, still references those values and fails to compile.

I created a simple patch to remove those values and instead use the already-set versions of them. That allows it to build.

tseng.patch

I'm relatively clueless as to how this bit of code works or the implications but I'll test and report back. I intentionally did not submit a merge, a code review here would be needed given my rusty dev skills.