sdm: Add support for adaptive variable refresh feature

1. Populate information about AVR feature support from sysfs node.
2. Initialize AVR information based on display mode and dynamic fps
   mode and set corresponding AVR flags.
3. Define debug property sdm.debug.disable_avr to disable avr feature.

Change-Id: I1bfbb9e1f9975468aa9eb6d6b575f317c658480e
CRs-Fixed: 1043833

sdm/include/utils/debug.h

@@ -74,6 +74,7 @@ class Debug {
   static bool IsRotatorSplitDisabled();
   static bool IsScalarDisabled();
   static bool IsUbwcTiledFrameBuffer();
+  static bool IsAVRDisabled();
   static bool GetProperty(const char *property_name, char *value);
   static bool SetProperty(const char *property_name, const char *value);