The method update_plmnsel() does not return the status word yet, which
causes pysim-prog.py to print an error message that does not influence
the functionality but does not look nice.
- preserve the status word that is returned with update_binary() and
return it properly like the other methods do.
Change-Id: I54e8e165f87365e8162b36d24efc8f0db62b66da
Related: SYS#4245