schemas: fix pid.json

Extend the schema by some properties which were not accounted for.
All of these should be supported based on looking at configurations and
grepping through phosphor-pid-control.

Tested: Schema Validator Pass

Change-Id: I4bd5b9aa51218844a12c643225d5fd80cc0f57aa
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
diff --git a/schemas/pid.json b/schemas/pid.json
index 098bdb0..9e6ae71 100644
--- a/schemas/pid.json
+++ b/schemas/pid.json
@@ -2,6 +2,7 @@
     "$schema": "http://json-schema.org/draft-07/schema#",
     "$defs": {
         "Pid": {
+            "additionalProperties": false,
             "type": "object",
             "properties": {
                 "CheckHysteresisWithSetpoint": {
@@ -86,7 +87,7 @@
                     }
                 },
                 "Type": {
-                    "type": "string"
+                    "const": "Pid"
                 },
                 "Zones": {
                     "type": "array",
@@ -99,6 +100,15 @@
                 },
                 "SetPointOffset": {
                     "type": "string"
+                },
+                "samplePeriod": {
+                    "type": "number",
+                    "minimum": 0
+                },
+                "FailSafePercent": {
+                    "type": "number",
+                    "minimum": 0,
+                    "maximum": 100
                 }
             },
             "required": [