drm/i915: extract ibx_irq_uninstall

Just like ibx_irq_preinstall. We'll call this from somewhere else in
the next patch.
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_irq.c

@@ -2904,7 +2904,6 @@ static void ironlake_irq_preinstall(struct drm_device *dev)
 	I915_WRITE(HWSTAM, 0xeffe);
 
 	GEN5_IRQ_RESET(DE);
-
 	if (IS_GEN7(dev))
 		I915_WRITE(GEN7_ERR_INT, 0xffffffff);
 
@@ -3277,6 +3276,19 @@ static int gen8_irq_postinstall(struct drm_device *dev)
 	return 0;
 }
 
+static void ibx_irq_uninstall(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	if (HAS_PCH_NOP(dev))
+		return;
+
+	GEN5_IRQ_RESET(SDE);
+
+	if (HAS_PCH_CPT(dev) || HAS_PCH_LPT(dev))
+		I915_WRITE(SERR_INT, 0xffffffff);
+}
+
 static void gen8_irq_uninstall(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -3348,12 +3360,7 @@ static void ironlake_irq_uninstall(struct drm_device *dev)
 
 	gen5_gt_irq_reset(dev);
 
-	if (HAS_PCH_NOP(dev))
-		return;
-
-	GEN5_IRQ_RESET(SDE);
-	if (HAS_PCH_CPT(dev) || HAS_PCH_LPT(dev))
-		I915_WRITE(SERR_INT, 0xffffffff);
+	ibx_irq_uninstall(dev);
 }
 
 static void i8xx_irq_preinstall(struct drm_device * dev)