HDMICEC: Disable CecController after the process of going to standby is completed

Move CecController disabling in a callback which is invoked after local
device's standby has finished.

This change helps to make sure the <Standby> message is broadcasted before
the HAL is disabled.

Bug: 253535259
Test: atest com.android.server.hdmi && atest CtsHdmiCecHostTestCases
Change-Id: I82f7dccf2a943166aa028159bf36b197d8dab08b