ANDROID: Rework misfit_status logic to work better with vendorhooks

With the trace_android_rvh_update_misfit_status() vendorhook
where it is, we may exit early leaving the rq->misfit_* values
uncleared, forcing the vendorhook logic to manage it.

This adjustment, suggested by Kuyo Chang, ensures that the
the values are cleared by default, and the vendorhook doesn't
need to manage anything if it returns zero for need_update.

Bug: 389223548
Suggested-by: Kuyo Chang <kuyo.chang@mediatek.com>
Change-Id: I957ebaf07550fd3f1bce5efbb8c83f9c7d88d5ec
Signed-off-by: John Stultz <jstultz@google.com>