SF: correct 90hz debug flags

debug.sf.set_idle_timer_ms > 0, debug.sf.use_90Hz == 0, was activating
boost to 90Hz. This corrects it so that if debug.sf.use_90Hz == 0,
then set_idle_timer has no effect.

Fixes: 124780321
Test: Manual systrace inspection
Change-Id: If926c086b5bdcf3645baa958bd19c7b163718728
1 file changed