mm-video: vidc: release registered buffers from driver

In some scenarios, component may restart from loaded to idle
state in the same context and it is resulting in the preapare
buf failure as previous buffers are not unregistered. Unregister
the buffers from driver while stopping the component.

b/11051201

Signed-off: Manikanta Kanamarlapudi<kmanikan@codeaurora.org>

Change-Id: I048cf715d2e83b05df99eaf10776cff0bbb2acd2