ANDROID: sched: time: Export symbols needed for schedutil module

Export symbols needed to allow building a schedutil-based vendor module
with GKI.

This is a small price to pay to give vendors the flexibility they need,
and avoids littering cpufreq_schedutil.c with many vendor hooks.

Bug: 170511085
Signed-off-by: Quentin Perret <qperret@google.com>
Change-Id: I8ff8bdb32df5d47124236819efba881c1a2a538d
(cherry picked from commit 34cd6916744b8b2d2107d2d5f10cbacb181e4f6c)
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>