sched/hmp: Use improved information for frequency notifications

Recent changes to scheduler guided frequency have started reporting
the maximum of the cpu load and the load of the top task on a CPU
to the governor. Use the same information to determine whether a
notification is necessary or not.

Change-Id: I1928c6cd0509952443a912ef54e0d72d5f75955d
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>