bcm2835_audio_release() calls vchi_service_close() and then
unconditionally calls vchi_service_release() with the same service
handle.

In the VCHI shim implementation, a successful vchi_service_close() calls
service_free(service). The subsequent vchi_service_release() therefore
dereferences a freed SHIM_SERVICE_T object when it reads
service->handle, resulting in a use-after-free panic.

vchi_service_release(), however, releases a reference which might block
vchi_service_close() from completing successfuly, so comment it out
instead of removing it altogether, until further testing is done.

MFC after: 2 weeks