[rilmodem] Refine SMS sending response value handling

By this change, the SMS is resent only  in cases it is worth of retrying.

Signed-off-by: Petri Takalokastari <petri.takalokastari@oss.tieto.com>
Merge pull request #179 from ptakalok/mosms

[rilmodem] Refine SMS sending response value handling