ANDROID: cpufreq: times: Remove per-UID time in state tracking

This removes the portion of commit c408992c ("ANDROID: cpufreq:
times: track per-uid time in state") adding per-UID tracking, while
preserving an added null check in the per-task tracking code.

Bug: 127641090
Signed-off-by: Connor O'Brien <connoro@google.com>
Change-Id: Iae3e0abef32cbbb9fdc674079973040be0060ac7