drm/i915: Clean up LVDS register handling harder

Minor fixup to d0669d00 ("drm/i915: Clean up LVDS register
handling") which intended to read lvds_reg just once at the
beginning of intel_lvds_init() and use that throughout the rest
of the function but accidentally missed one register readout.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20151107141244.AB7616E242@gabe.freedesktop.orgSigned-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_lvds.c

@@ -1164,8 +1164,7 @@ void intel_lvds_init(struct drm_device *dev)
 	DRM_DEBUG_KMS("detected %s-link lvds configuration\n",
 		      lvds_encoder->is_dual_link ? "dual" : "single");
 
-	lvds_encoder->a3_power = I915_READ(lvds_encoder->reg) &
-				 LVDS_A3_POWER_MASK;
+	lvds_encoder->a3_power = lvds & LVDS_A3_POWER_MASK;
 
 	lvds_connector->lid_notifier.notifier_call = intel_lid_notify;
 	if (acpi_lid_notifier_register(&lvds_connector->lid_notifier)) {