some fixes to CALLA - update SP early
some fixes to CALLA - update SP early

contiki-os/mspsim,ransford/mspsim,cmorty/mspsim,joakimeriksson/mspsim,fvdnabee/mspsim,joakimeriksson/mspsim,ransford/mspsim,nfi/mspsim,mspsim/mspsim,mspsim/mspsim,nfi/mspsim,cmorty/mspsim,contiki-os/mspsim,fvdnabee/mspsim