sched: Fix out of bounds array access in sched_reset_all_window_stats()

A new reset reason code "FREQ_AGGREGATE_CHANGE" is added to
reset_reason_code enum but the corresponding string array is not
updated. Fix this.

Change-Id: I2a17d95328bef91c4a5dd4dde418296efca44431
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>