Remove priv-callback support from bmcweb

priv-callback is valid only for IPMI modem callback, which
was never used, and it's decided to deprecate the same
https://gerrit.openbmc-project.xyz/#/c/openbmc/docs/+/26839/
Removing the support in redfish now.

Tested:
1. Verified callback role was not in list in Get of
https://<BMC IP>/redfish/v1/AccountService/Roles/
2. Redfish validator passed for this change.

Change-Id: Ia16fb584a07bbdf29197cd5dd54e7a9682627c19
Signed-off-by: Richard Marian Thomaiyar <richard.marian.thomaiyar@linux.intel.com>
diff --git a/redfish-core/lib/account_service.hpp b/redfish-core/lib/account_service.hpp
index 0658f3f..fa10c04 100644
--- a/redfish-core/lib/account_service.hpp
+++ b/redfish-core/lib/account_service.hpp
@@ -78,10 +78,6 @@
     {
         return "Administrator";
     }
-    else if (role == "priv-callback")
-    {
-        return "Callback";
-    }
     else if (role == "priv-user")
     {
         return "ReadOnly";
@@ -98,10 +94,6 @@
     {
         return "priv-admin";
     }
-    else if (role == "Callback")
-    {
-        return "priv-callback";
-    }
     else if (role == "ReadOnly")
     {
         return "priv-user";
diff --git a/redfish-core/lib/roles.hpp b/redfish-core/lib/roles.hpp
index d170a5c..4256c7e 100644
--- a/redfish-core/lib/roles.hpp
+++ b/redfish-core/lib/roles.hpp
@@ -28,10 +28,6 @@
     {
         return "Administrator";
     }
-    else if (priv == "priv-callback")
-    {
-        return "Callback";
-    }
     else if (priv == "priv-user")
     {
         return "ReadOnly";
@@ -59,10 +55,6 @@
     {
         privArray = {"Login", "ConfigureSelf"};
     }
-    else if (role == "Callback")
-    {
-        privArray = {"Login"};
-    }
     else
     {
         return false;