kms: init dga using xf86DiDGAInit

[Keith Packard]

You posted a patch to the radeon driver to call xf86DiDGAInit to get
some DGA-using games working again. Please read my recent posting to
xorg-devel about why this is a bad idea -- it exposes the system to
some serious potential badness.

I've posted a patch to the server for review that will enable the
input and modesetting portions of DGA without the direct-mapping
elements, this eliminates the need to initialize DGA from your driver.
-- 
keith.packard at intel.com