Revert "allow override of cabc file via property"

A quick search reveals that only 1 device uses this - kona.

Instead of adding a system prop for this, that one device
can add its own AdaptiveBacklight class. This allows kona to
use AdaptiveBacklight without having to modify the common class.

This reverts commit c11396ecc6.

Change-Id: Id912091f64da39a10d30c9770f248cf6467e8760

cmhw/org/cyanogenmod/hardware/AdaptiveBacklight.java

@@ -16,8 +16,6 @@
 
 package org.cyanogenmod.hardware;
 
-import android.os.SystemProperties;
-
 import org.cyanogenmod.internal.util.FileUtils;
 
 /**
@@ -26,8 +24,7 @@ import org.cyanogenmod.internal.util.FileUtils;
  */
 public class AdaptiveBacklight {
 
-    private static final String FILE_CABC = SystemProperties.get(
-            "ro.cm.hardware.cabc", "/sys/class/lcd/panel/power_reduce");
+    private static final String FILE_CABC = "/sys/class/lcd/panel/power_reduce";
 
     /**
      * Whether device supports an adaptive backlight technology.