allow override of cabc file via property

Note 8's cabc is implemented in mdnie instead of the panel
file like other smdk4x12 devices.

Change-Id: I9bd7c4bb5899cd323e4f6861bf7ceb61f459da05

cmhw/org/cyanogenmod/hardware/AdaptiveBacklight.java

@@ -18,6 +18,8 @@ package org.cyanogenmod.hardware;
 
 import org.cyanogenmod.hardware.util.FileUtils;
 
+import android.os.SystemProperties;
+
 import java.io.File;
 
 /**
@@ -26,7 +28,7 @@ import java.io.File;
  */
 public class AdaptiveBacklight {
 
-    private static String FILE_CABC = "/sys/class/lcd/panel/power_reduce";
+    private static String FILE_CABC = SystemProperties.get("ro.cm.hardware.cabc", "/sys/class/lcd/panel/power_reduce");
 
     /**
      * Whether device supports an adaptive backlight technology.