Fix potential deadlock with SensorObserver.

Sensor Observer grabs it's own lock (mSOLock) when voting for a display
mode, which then grabs the global DMD lock (mLock).
When printing out the dump() method, DMD holds mLock, then calls into
SensorObserver which grabs the mSOLock.  This can cause a deadlock.

There's no reason to hold mLock when calling SensorObserver's dump()
method, so fix that.

Test: adb shell dumpsys display
Bug: 210086128
Change-Id: Idf685f94b818f04f30bee5b85a503f64d448291a
(cherry picked from commit 8f808c5d79)

services/core/java/com/android/server/display/DisplayModeDirector.java

@@ -41,7 +41,6 @@ import android.os.IThermalEventListener;
 import android.os.IThermalService;
 import android.os.Looper;
 import android.os.Message;
-import android.os.PowerManager;
 import android.os.RemoteException;
 import android.os.ServiceManager;
 import android.os.SystemClock;
@@ -618,10 +617,11 @@ public class DisplayModeDirector {
             mAppRequestObserver.dumpLocked(pw);
             mBrightnessObserver.dumpLocked(pw);
             mUdfpsObserver.dumpLocked(pw);
-            mSensorObserver.dumpLocked(pw);
             mHbmObserver.dumpLocked(pw);
             mSkinThermalStatusObserver.dumpLocked(pw);
         }
+
+        mSensorObserver.dump(pw);
     }
 
     private void updateVoteLocked(int priority, Vote vote) {
@@ -2241,7 +2241,7 @@ public class DisplayModeDirector {
             }
         }
 
-        void dumpLocked(PrintWriter pw) {
+        void dump(PrintWriter pw) {
             pw.println("  SensorObserver");
             synchronized (mSensorObserverLock) {
                 pw.println("    mIsProxActive=" + mIsProxActive);