drm/i915: don't enable FDI & transcoder interrupts after all

We can enable some safely, but FDI and transcoder interrupts can occur
and block other interrupts from being detected (like port hotplug
events).  So keep them disabled by default (they can be re-enabled for
debugging display bringup, but should generally be off).
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_irq.c

@@ -316,6 +316,8 @@ static void i915_hotplug_work_func(struct work_struct *work)
 	struct drm_mode_config *mode_config = &dev->mode_config;
 	struct intel_encoder *encoder;
 
+	DRM_DEBUG_KMS("running encoder hotplug functions\n");
+
 	list_for_each_entry(encoder, &mode_config->encoder_list, base.head)
 		if (encoder->hot_plug)
 			encoder->hot_plug(encoder);
@@ -1649,9 +1651,7 @@ static int ironlake_irq_postinstall(struct drm_device *dev)
 	} else {
 		hotplug_mask = SDE_CRT_HOTPLUG | SDE_PORTB_HOTPLUG |
 			       SDE_PORTC_HOTPLUG | SDE_PORTD_HOTPLUG;
-		hotplug_mask |= SDE_AUX_MASK | SDE_FDI_MASK | SDE_TRANS_MASK;
-		I915_WRITE(FDI_RXA_IMR, 0);
-		I915_WRITE(FDI_RXB_IMR, 0);
+		hotplug_mask |= SDE_AUX_MASK;
 	}
 
 	dev_priv->pch_irq_mask = ~hotplug_mask;