greybus: remove obsolete SVC result codes

The "busy" SVC result codes are gone from the spec. Delete them.

Testing Done: compile.

Signed-off-by: Marti Bolivar <mbolivar@leaflabs.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>