drm/i915: Remove "VLV magic" from irq setup

No clue what this is supposed to achieve. I think it's been there since
the very beginning, so presumably some kind of kludge for very early
silicon. Let's just throw it out.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460382992-28728-2-git-send-email-ville.syrjala@linux.intel.comReviewed-by: Imre Deak <imre.deak@intel.com>

drivers/gpu/drm/i915/i915_irq.c

@@ -3319,12 +3319,6 @@ static void valleyview_irq_preinstall(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	/* VLV magic */
-	I915_WRITE(VLV_IMR, 0);
-	I915_WRITE(RING_IMR(RENDER_RING_BASE), 0);
-	I915_WRITE(RING_IMR(GEN6_BSD_RING_BASE), 0);
-	I915_WRITE(RING_IMR(BLT_RING_BASE), 0);
-
 	gen5_gt_irq_reset(dev);
 
 	I915_WRITE(DPINVGTT, DPINVGTT_STATUS_MASK);