cpufreq: sched: WALT: don't apply capacity margin twice

With WALT all the scheduler classes' load are accounted in scr->cfs and
schedfreq adds capacity margin.  At present, at tick path, scheduler
adds capacity margin which as well.  Therefore the margin applied
twice.

Fix such error by removing applying of capacity margin at tick path.

Change-Id: Id7d8cc73b2e4eec70b274ca66e09bb0b16bf6f09
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>