Declare first tunnel frame ready event for video peek

This commit declares the OMX_EventOnFirstTunnelFrameReady event that
lets OMX components signal to the framework that the component is
ready for video peek.

Bug: 157501309
Test: Currently untested, full CTS coverage coming soon
CTS-Coverage-Bug: 157501309
Change-Id: Ie9a88b8fb5c73924bd2fb62573949082dad0374e