Fix fd leak in media.codec

If codec process is killed quickly after starting to decode, there may be
fd leak in media.codec.
Before all buffers are ready, SimpleSoftOMXComponent keeps the state as
OMX_StateLoaded. At this time, codec process is killed,
OMXNodeInstance::onObserverDied() -> freeNode()->
SimpleSoftOMXComponent::getState(...). And the state is OMX_StateLoaded.
Currently, the freeActiveBuffers() is not called at state OMX_StateLoaded
and the allocated buffers are leaked.

Solution is to free allocated buffers at state OMX_StateLoaded.

Bug: 135003556
Test: Some apps use SoundPool to play sound. Quickly kill the process
after start play.
Change-Id: I9de74cd2cb63e1aa96fd2397f3a72d976d1b2183