DP_PTASK: Fix warning may be used uninitialized
It could be unitialized only in case if we add new enum be_ptask_schedule
Currently, we have only BE_PTASK_SCHEDULE_FROM_NOW and
BE_PTASK_SCHEDULE_FROM_LAST which are properly covered in switch case.
src/providers/dp_ptask.c:200: warning: ‘tv’ may be used uninitialized in this function
Reviewed-by: Pavel Březina <pbrezina@redhat.com>