drm/i915: Use GEN8_MASTER_IRQ_CONTROL consistently

Use GEN8_MASTER_IRQ_CONTROL instead of DE_MASTER_IRQ_CONTROL or
MASTER_INTERRUPT_ENABLE with the GEN8_MASTER_IRQ register. They're
all bit 31 so there's no actual bug here, but let's be consistent
which name we use for the bit.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460571598-24452-2-git-send-email-ville.syrjala@linux.intel.comReviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_irq.c

@@ -1855,7 +1855,7 @@ static irqreturn_t cherryview_irq_handler(int irq, void *arg)
 		 * signalled in iir */
 		valleyview_pipestat_irq_handler(dev, iir);
 
-		I915_WRITE(GEN8_MASTER_IRQ, DE_MASTER_IRQ_CONTROL);
+		I915_WRITE(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL);
 		POSTING_READ(GEN8_MASTER_IRQ);
 	} while (0);
 
@@ -3796,7 +3796,7 @@ static int gen8_irq_postinstall(struct drm_device *dev)
 	if (HAS_PCH_SPLIT(dev))
 		ibx_irq_postinstall(dev);
 
-	I915_WRITE(GEN8_MASTER_IRQ, DE_MASTER_IRQ_CONTROL);
+	I915_WRITE(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL);
 	POSTING_READ(GEN8_MASTER_IRQ);
 
 	return 0;
@@ -3813,7 +3813,7 @@ static int cherryview_irq_postinstall(struct drm_device *dev)
 		vlv_display_irq_postinstall(dev_priv);
 	spin_unlock_irq(&dev_priv->irq_lock);
 
-	I915_WRITE(GEN8_MASTER_IRQ, MASTER_INTERRUPT_ENABLE);
+	I915_WRITE(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL);
 	POSTING_READ(GEN8_MASTER_IRQ);
 
 	return 0;