Revert "drm/i915: Enable PSR by default on Valleyview and Cherryview."

This reverts commit a38c274f.

PSR causes all sorts of vblank wait timeouts and whanot on CHV. Disable
it again.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Fixes: a38c274f ("drm/i915: Enable PSR by default on Valleyview and Cherryview.")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1457543247-13987-2-git-send-email-ville.syrjala@linux.intel.com
Link: http://patchwork.freedesktop.org/patch/msgid/1457543247-13987-2-git-send-email-ville.syrjala@linux.intel.comAcked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

drivers/gpu/drm/i915/intel_psr.c

@@ -781,8 +781,7 @@ void intel_psr_init(struct drm_device *dev)
 
 	/* Per platform default */
 	if (i915.enable_psr == -1) {
-		if (IS_HASWELL(dev) || IS_BROADWELL(dev) ||
-		    IS_VALLEYVIEW(dev) || IS_CHERRYVIEW(dev))
+		if (IS_HASWELL(dev) || IS_BROADWELL(dev))
 			i915.enable_psr = 1;
 		else
 			i915.enable_psr = 0;