media/hardware/HardwareAPI.h: Added PrepareForAdaptivePlaybackParams

This is the param struct used by stagefright to notify codec that
the playback may include resolution changes, so that it can prepare
accordingly to avoid port reconfiguration.

Change-Id: I64e53b7ebf74c4f9d07cc9fe0cd65be55f666afe
Signed-off-by: Lajos Molnar <lajos@google.com>
Related-to-bug: 7093648