sched/cap_gov: raise again the up_th and use it to pick cap level

If we use the capacity to select the next OPP to run at, it is
quite likely that we will cross the up_th of that OPP right after
the freq switch. Let's use the up_thresholds instead to achieve
more stability.

Signed-off-by: Juri Lelli <juri.lelli@arm.com>