convert to new screen conversion apis

[Dave Airlie]

I've pushed a script to util/modular made of find/sed

x-driver-screen-scrn-conv.sh

it should convert all instances of xf86Screens and screenInfo.screens
that match for easy conversion.

It won't get rid of all of them but it will at least make it easier to
spot what is left.

I intend to bomb as many drivers as I can pretty soon, I'm going to
assume to leave vmware alone and anyone else who shouts at me before I
get around to it.

Dave.