staging: vchiq: move vchiq_release_message() into vchiq

staging: vchiq: move vchiq_release_message() into vchiq

For messages with a reason different from VCHIQ_MESSAGE_AVAILABLE the
responsibility for releasing them is kept in vchi, in other words,
services don't need to worry about it. As we're trying to unify vchi and
vchiq, move the release code into vchiq.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/20200527115400.31391-10-nsaenzjulienne@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>