lrdp_v2: Fix DL tasks prio in taskdump module

DL (SCHED_DEADLINE) tasks don't have any priority. They will be
scheduled in EDF (Early Deadline First) fashion. In task_struct,
the prio for such tasks would be -1. The current code treats
prio as an unsigned int and prints DL task prio as 4294967295.
Cast the prio to int before printing it.

Change-Id: Ib92417eeb361fc15d9d536eafe5dfe1baec06d20