Redfish: Implement ResetBios action

This action resets the BIOS attributes to default.

Tested:
GET test:
1. $ curl -k -H "X-Auth-Token: $token" https://${bmc}/redfish/v1/Systems/system
{
  ...
  "Bios": {
    "@odata.id": "/redfish/v1/Systems/system/Bios"
  },
  ...
}
2. $ curl -k -H "X-Auth-Token: $token" https://${bmc}/redfish/v1/Systems/system/Bios
{
  "@odata.id": "/redfish/v1/Systems/system/Bios",
  "@odata.type": "#Bios.v1_1_0.Bios",
  "Actions": {
    "#Bios.ResetBios": {
      "target": "/redfish/v1/Systems/system/Bios/Actions/Bios.ResetBios"
    }
  },
  "Description": "BIOS Configuration Service",
  "Id": "BIOS",
  "Name": "BIOS Configuration"
}

POST test:
1. Change gard list:
 # ./gard list
 No GARD entries to display
 # ./gard create /Sys0/Node0/Proc1/EQ1/EX1/Core0
 # ./gard list
  ID       | Error    | Type       | Path
 -----------------------------------------------------------------------
  00000001 | 00000000 | Manual     | /Sys0/Node0/Proc1/EQ1/EX1/Core0
 =======================================================================
2. Reset bios:
 # curl -k -H "X-Auth-Token: $token" -X POST https://${bmc}/redfish/v1/Systems/system/Bios/Actions/Bios.ResetBios
3. Check gard list again:
 # ./gard list
 No GARD entries to display

Validator tool test:
 Counter({'pass': 3001, 'skipOptional': 2475, 'metadataNamespaces': 1605,
 'passGet': 191, 'serviceNamespaces': 72, 'invalidPropertyValue': 10,
 'passAction': 7, 'optionalAction': 6, 'warningPresent': 6, 'warnDeprecated':
 2, 'unverifiedComplexAdditional': 1})
 Validation has succeeded.

Signed-off-by: Carol Wang <wangkair@cn.ibm.com>
Change-Id: I0cba966bfde04566001b6df07ad15217f627c327
diff --git a/redfish-core/lib/systems.hpp b/redfish-core/lib/systems.hpp
index ce12ed7..93eb403 100644
--- a/redfish-core/lib/systems.hpp
+++ b/redfish-core/lib/systems.hpp
@@ -1710,6 +1710,9 @@
         res.jsonValue["LogServices"] = {
             {"@odata.id", "/redfish/v1/Systems/system/LogServices"}};
 
+        res.jsonValue["Bios"] = {
+            {"@odata.id", "/redfish/v1/Systems/system/Bios"}};
+
         res.jsonValue["Links"]["ManagedBy"] = {
             {{"@odata.id", "/redfish/v1/Managers/bmc"}}};