control: json: Correct hysteresis definitions

The action target_from_group_max has been implementing the reversed
definitions of positive hysteresis and negative hysteresis. The positive
hysteresis should be for the value increasing case and vice versa. This
commit corrects that in source code and events.md.

Signed-off-by: Chau Ly <chaul@amperecomputing.com>
Change-Id: I1b84884d16d5f20d0fdcd9033188ffd31e91f907
2 files changed