Change nullability of inheriting function of PinPrivacyPreferenceController

Test: None
Bug: b/292569343
(cherry picked from commit a7d7eb9a16951c7e23dc82c915d47321254c3c31)
(cherry picked from commit 4ca80e6013d929cefb227958183b1f053b052cc5)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:05514d0f4d5b6603da6a79881becb0b768e586a6)
Merged-In: Idbfa244921957be2bba3cd02e5e873e81e8807d8
Change-Id: Idbfa244921957be2bba3cd02e5e873e81e8807d8
1 file changed