sched/fair: use sched_capacity_margin_up/down array values

Sched_capacity_margin_up/down arrays have CPU specific values which
should be used in task_fits_capacity() instead of values available
in sysctl_sched_capacity_margin_up/down arrays for margin checks.

Change-Id: I08f2e0f1d76492a13745f1aafafbfcd5f033b8aa
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>