schemas: legacy: enumerate Thresholds: 'Direction'

Tested: Schema Validator Pass

Change-Id: I5ecfa12863bdab457bae50d22fbd96628ec2024b
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
diff --git a/schemas/legacy.json b/schemas/legacy.json
index be634dc..a4b5cf0 100644
--- a/schemas/legacy.json
+++ b/schemas/legacy.json
@@ -881,7 +881,7 @@
                 "items": {
                     "properties": {
                         "Direction": {
-                            "type": "string"
+                            "enum": ["less than", "greater than"]
                         },
                         "Hysteresis": {
                             "type": "number"