Fix deadlock issue.

It might cause deadlock sometimes:

The locking order of setEventsMask is:
    registerDisplayListener -> <DMG.mLock> -> setEventsMask -> <class lock>;

The Locking order of handleMessage is:
    Looper.loop -> Looper.loopOnce -> Handler.dispatchMessage -> handleMessage -> <class lock>;

Therefore, when the registerDisplayListener is called by client,
the DisplayListenerDelegate.handleMessage also called by DMS's callback,
at this time, if the method with DMG.mLock is called in handleMessage(),
it will lead to deadlock.

Test: (For example)
Thread A:
DisplayListenerDelegate.handleMessage() -> <class lock>
DisplayListener.onDisplayChanged() -> DMG.getCompatibleDisplay() ->
DMG.getDisplayInfo() -> <DMS.mLock>

Thead B:
DMG.registerDisplayListener() -> <DMS.mLock> -> DisplayListenerDelegate.setEventsMask() -> <class lock>

Signed-off-by: jiayongqiang <jiayongqiang@xiaomi.com>
Change-Id: Ie1a8728339c16fa8f4c4f5c758821c836fa1c96b