greybus: svc: support status in svc_intf_activate response
Update per Greybus spec. Status attribute added to activate
response to return more detailed information about errors during
activate. If the Greybus response is GB_OP_SUCCESS, the caller
must also check the status attribute in the response to determine
if any other errors occurred.
Testing done: along with matchine firmware change, verified that modules
were detected and enumerated as expected.