cpufreq: schedutil: fix CPU util when WALT is enabled

Right now, when WALT is enabled, we always end up using utilization
from WALT which is broken as we need to consider uclamp as well.
Fix the issue by taking uclamp into account.

Change-Id: Ie1a06d270a176771fc1c9a2474a27327637fa782
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>