greybus: svc: add interface resume operation

Add the AP implementation for the Greybus SVC Interface Resume
Operation. This operation allows the AP to request the SVC to resume an
Interface which was previously SUSPENDED, allowing it to later be
ENUMERATED.

Signed-off-by: David Lin <dtwlin@google.com>
Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Alex Elder <elder@linaro.org>