HDMICEC: Add lock for CEC standby.

TCL issue 2-7 "CEC devices will not enter standby mode with TV sometimes."

When going to standby use a WakeLock that will keep the system turned on until the standby process is completed and the WakeLock is released.

Bug: 253535259
Bug: 230663730
Test: atest com.android.server.hdmi

Change-Id: Ib6cba8c59e541a4c8abd5af8ac4302e22ebf9077