lib: cmsis_rtos: Fix Periodic timer

This commit changes the behaviour of the CMSIS-RTOS periodic timers to
have an initial timeout equal to the periodic timeout instead of
executing the callback function directly when calling the
osTimerStart(...); function.

This behavioural change is according to the CMSIS-RTOS specification.

Signed-off-by: Måns Ansgariusson <Mans.Ansgariusson@AssaAbloy.com>