greybus: svc: Kill unnecessary wrapper functions

Not sure why they were created, but there is no need for them. Kill
them.

Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>