cpufreq: schedutil: Add tracepoints for debugging

Add trace points when load gets updated and when frequency is chosen
to facilitate better debugging.

Change-Id: Ib19911a03fc941bc7db76ab07394e152d0572871
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>
[avilaj@codeaurora.org: Fix some conflicts introduced by reordering this patch]
Signed-off-by: Jonathan Avila <avilaj@codeaurora.org>