Fix invalid enum value in User/Ldap/Config.interface.yaml

The interfaces sets the default value for a enum property to 0, which
causes the generated server.hpp file contains code like:

    SearchScope _lDAPSearchScope = SearchScope::0;

Fix it by specify the enum value instead of 0.

Tested: Verify the generated code becomes below and pass the build.

    SearchScope _lDAPSearchScope = SearchScope::sub;

Change-Id: I509b6968d32dec38d1592103df9821b2fc99b5d6
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/xyz/openbmc_project/User/Ldap/Config.interface.yaml b/xyz/openbmc_project/User/Ldap/Config.interface.yaml
index 34babf1..6b0a1e5 100644
--- a/xyz/openbmc_project/User/Ldap/Config.interface.yaml
+++ b/xyz/openbmc_project/User/Ldap/Config.interface.yaml
@@ -29,7 +29,7 @@
       type: enum[self.SearchScope]
       description: >
           Specifies the search scope:subtree, one level or base object.
-      default: 0
+      default: sub
       errors:
         - xyz.openbmc_project.Common.Error.InternalFailure
     - name: LDAPType