drm/i915: Restore physical HWS_PGA after resume

drm/i915: Restore physical HWS_PGA after resume

By always setting up the HWS register for both physical and virtual
address variations during render ring we can reduce the number of
different special cases that get set up at varying different times
during module load.

Fixes regression from

commit 4a39344b8ef3f30d4974d0c05da3e2e325db5adf
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Oct 17 11:32:57 2012 +0200

    drm/i915: don't save/restore HWS_PGA reg for kms

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>