sched: EAS: schedfreq: fix CPU util over estimation

WALT CPU utilization reports CPU load of all the scheduler classes.
Therefore adding RT class's load additionally will cause frequency
overshooting.  Fix such issue by not accounting RT class load when
requesting capacity.

Change-Id: I29600d7af7ca8c00e0d2ff1e13872024ccaa72bf
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>