[Cooker] avview dependency on ati.2

[Pascal Terjan]

After someone reported on irc installing avview broke is X by installing 
ati.2 while is card is not an ATI, I looked on the website and did not 
found such a dependency :

   Requirements: TV input capable card with Xv support, Tcl/Tk 8.4.x or 
later.
		 libzvbi from http://zapping.sf.net/
		 ffmpeg-0.4.6 from http://ffmpeg.sf.net/

So the ati.2 is only needed if you have an ATI which has no Xv without 
it. I don't know what is the best solution but keeping non ATI drivers 
would limit the impact of useless ati.2 installation.