Remove priv-callback support

priv-callback is deprecated as this privilege is applicable
only to IPMI modem callback, which will not be supported in OpenBmc.
In order to avoid confusion with this role, the same has been
deprecated. Refer https://gerrit.openbmc-project.xyz/#/c/openbmc/docs/+/26839/

Tested:
1. Verified user management works as expected
2. Verified existing user with priv-callback is rolled as no-acess user.

(From meta-phosphor rev: 96e5ce1e16476e984fc805c99f01351e1e310e97)

Change-Id: Ifea3986d9f4b55359138597ee0b6264870f1af0a
Signed-off-by: Richard Marian Thomaiyar <richard.marian.thomaiyar@linux.intel.com>
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-phosphor/recipes-phosphor/users/phosphor-user-manager_git.bb b/meta-phosphor/recipes-phosphor/users/phosphor-user-manager_git.bb
index 4ccf0c3..8a2971c 100644
--- a/meta-phosphor/recipes-phosphor/users/phosphor-user-manager_git.bb
+++ b/meta-phosphor/recipes-phosphor/users/phosphor-user-manager_git.bb
@@ -23,8 +23,8 @@
 USERADD_PACKAGES = "${PN} phosphor-ldap"
 DBUS_PACKAGES = "${USERADD_PACKAGES}"
 # add groups needed for privilege maintenance
-GROUPADD_PARAM_${PN} = "priv-admin; priv-operator; priv-user; priv-callback "
-GROUPADD_PARAM_phosphor-ldap = "priv-admin; priv-operator; priv-user; priv-callback "
+GROUPADD_PARAM_${PN} = "priv-admin; priv-operator; priv-user "
+GROUPADD_PARAM_phosphor-ldap = "priv-admin; priv-operator; priv-user "
 
 DBUS_SERVICE_${PN} += "xyz.openbmc_project.User.Manager.service"
 FILES_phosphor-ldap += " \