drm/i915: g4x/vlv: fix dp aux interrupt mask

Fix typo possibly leading to timed out DP aux transactions on ports C,D.

Introduced in:

Commmit 4aeebd74
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Oct 31 09:53:36 2013 +0100

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=72210
Signed off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -2138,7 +2138,8 @@
 #define   DP_AUX_CHANNEL_D_INT_STATUS_G4X	(1 << 6)
 #define   DP_AUX_CHANNEL_C_INT_STATUS_G4X	(1 << 5)
 #define   DP_AUX_CHANNEL_B_INT_STATUS_G4X	(1 << 4)
-#define   DP_AUX_CHANNEL_MASK_INT_STATUS_G4X	(1 << 4)
+#define   DP_AUX_CHANNEL_MASK_INT_STATUS_G4X	(7 << 4)
+
 /* SDVO is different across gen3/4 */
 #define   SDVOC_HOTPLUG_INT_STATUS_G4X		(1 << 3)
 #define   SDVOB_HOTPLUG_INT_STATUS_G4X		(1 << 2)