Legacy camera shim: add option to free buffers earlier

This option allows HAL to opt in for the behavior that will free
cached buffers earlier if the libhardware HAL implementation
doesn't cache/reference the cached buffers internally.

Test: buffers are freed earlier when the property is set
Bug: 111850884
Change-Id: I3a10b288c7160c86dc7d3a30d04b5c4903917731