IOMX: Add prepareForAdaptivePlayback method

prepareForAdaptivePlayback is the fallback mechanism to support
seamless resolution change for devices that do not support dynamic
output buffers.  It is up to the codecs to handle this appropriately,
but codecs that do not handle dynamic output buffers would
request enough buffers up to the requested size in this method
to avoid port reconfiguration on resolution changes.

Change-Id: I58d4aa8ef1359ea3472735bbe9140c3132039b3d
Signed-off-by: Lajos Molnar <lajos@google.com>
Bug: 10192531
Related-to-bug: 7093648