drm/i915: Always use SDVO_B detect bit for SDVO output detection.

After the following commit is shipped, the SDVO C detection will depend on
the SDVO_C/DP detion bit.
commit 13520b0
Author: Kristian Høgsberg <krh@redhat.com>
Date:   Fri Mar 13 15:42:14 2009 -0400

    drm/i915: Read the right SDVO register when detecting SVDO/HDMI.

According to the spec we should continue to detect the SDVO_B/C based on
the SDVO_B detection bit.  The new detection bit on G4X platform is for
the HDMI_C detection rather than SDVO_C detection.

https://bugs.freedesktop.org/show_bug.cgi?id=20639

Signed-off-by: Ma Ling <ling.ma@intel.com>
Acked-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/intel_display.c

@@ -3218,30 +3218,30 @@ static void intel_setup_outputs(struct drm_device *dev)
 			intel_dp_init(dev, PCH_DP_D);
 
 	} else if (IS_I9XX(dev)) {
-		int found;
-		u32 reg;
+		bool found = false;
 
 		if (I915_READ(SDVOB) & SDVO_DETECTED) {
 			found = intel_sdvo_init(dev, SDVOB);
 			if (!found && SUPPORTS_INTEGRATED_HDMI(dev))
 				intel_hdmi_init(dev, SDVOB);
+
 			if (!found && SUPPORTS_INTEGRATED_DP(dev))
 				intel_dp_init(dev, DP_B);
 		}
 
 		/* Before G4X SDVOC doesn't have its own detect register */
-		if (IS_G4X(dev))
-			reg = SDVOC;
-		else
-			reg = SDVOB;
 
-		if (I915_READ(reg) & SDVO_DETECTED) {
+		if (I915_READ(SDVOB) & SDVO_DETECTED)
 			found = intel_sdvo_init(dev, SDVOC);
-			if (!found && SUPPORTS_INTEGRATED_HDMI(dev))
+
+		if (!found && (I915_READ(SDVOC) & SDVO_DETECTED)) {
+
+			if (SUPPORTS_INTEGRATED_HDMI(dev))
 				intel_hdmi_init(dev, SDVOC);
-			if (!found && SUPPORTS_INTEGRATED_DP(dev))
+			if (SUPPORTS_INTEGRATED_DP(dev))
 				intel_dp_init(dev, DP_C);
 		}
+
 		if (SUPPORTS_INTEGRATED_DP(dev) && (I915_READ(DP_D) & DP_DETECTED))
 			intel_dp_init(dev, DP_D);
 	} else