Dual-headed configuration using xrandr on GM45 intel query

[garrone]

I was able to make the two internal channels assign to the two TMDS
outputs by using the -crtc option, as follows.
xrandr --fb 1680x2100 \
	--output VGA --off\
 	--output LVDS --off\
 	--output TMDS-1 --pos 0x1050 --mode 1680x1050 --crtc 0\
 	--output TMDS-2 --mode 1680x1050 --above TMDS-1 --crtc 1\
 	--output TV --off