trace/sched: set priority to 150 for deadline tasks

As deadline tasks doesn't have priority, their priority is set
to -1. If there are any deadline tasks in the system, chrome/tracing
doesn't show results as expected as it can't recognize tasks with
priority -1. Fix it by using 150 as priority for deadline tasks.

Change-Id: I49b43f77b97ebfe6d79a7c9e9ec346ea60e79768
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>