schemas: legacy: constrain 'AllowedFailures'

AllowedFailures cannot be negative.

Tested: Schema Validator Pass

Change-Id: Ie22e6e5ddb2f1b936488a2fd06b577b397f82760
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
diff --git a/schemas/legacy.json b/schemas/legacy.json
index ee3db1d..0000894 100644
--- a/schemas/legacy.json
+++ b/schemas/legacy.json
@@ -875,7 +875,9 @@
                 "type": ["string", "array"]
             },
             "AllowedFailures": {
-                "type": "number"
+                "type": "number",
+                "multipleOf": 1,
+                "minimum": 0
             },
             "AlphaF": {
                 "type": "number"