drm/i915: don't forget to uninstall the PM IRQs

It's the only thing missing, apparently.

v2: - Fix typo (Ben).
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

@@ -3364,6 +3364,8 @@ static void ironlake_irq_uninstall(struct drm_device *dev)
 		I915_WRITE(GEN7_ERR_INT, I915_READ(GEN7_ERR_INT));
 
 	GEN5_IRQ_FINI(GT);
+	if (INTEL_INFO(dev)->gen >= 6)
+		GEN5_IRQ_FINI(GEN6_PM);
 
 	if (HAS_PCH_NOP(dev))
 		return;