Revert "drm/i915: shut up gen8+ SDE irq dmesg noise"

This reverts

commit 97e5ed1111dcc5300a0f59a55248cd243937a8ab
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Fri Oct 23 10:56:12 2015 +0200

    drm/i915: shut up gen8+ SDE irq dmesg noise

With the proper fix ("drm/i915: fix the SDE irq dmesg warnings
properly") reliably in place, bring back the error message.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448462843-32739-2-git-send-email-jani.nikula@intel.com

drivers/gpu/drm/i915/i915_irq.c

@@ -2365,13 +2365,9 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg)
 				spt_irq_handler(dev, pch_iir);
 			else
 				cpt_irq_handler(dev, pch_iir);
-		} else {
-			/*
-			 * Like on previous PCH there seems to be something
-			 * fishy going on with forwarding PCH interrupts.
-			 */
-			DRM_DEBUG_DRIVER("The master control interrupt lied (SDE)!\n");
-		}
+		} else
+			DRM_ERROR("The master control interrupt lied (SDE)!\n");
+
 	}
 
 	I915_WRITE_FW(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL);