drm/i915: Unconditionally check gmch pfit state

Now that we recompute the pipe config for all CRTCs that have changed
we don't have problems with stale configuration data for the global
pfit and can remove this hack. Yay!

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>