sdm845-common: Fix restoring default LiveDisplay mode

* Call DisplayModes::setDisplayMode(modeID, false) in the constructor
* Move sysfs nodes chown/chmod to from 'on boot' to on init' so that
  they have proper perms right away.

Change-Id: I51ee19136688f83703e85b76d5219e5a567bbaa3

livedisplay/DisplayModes.cpp

@@ -53,6 +53,8 @@ DisplayModes::DisplayModes() : mDefaultModeId(0) {
             break;
         }
     }
+
+    setDisplayMode(mDefaultModeId, false);
 }
 
 // Methods from ::vendor::lineage::livedisplay::V2_0::IDisplayModes follow.