s4:rpc-server:samr: fix setting of lockout duration < lockout window

s4:rpc-server:samr: fix setting of lockout duration < lockout window

This should return NT_STATUS_INVALID_PARAMETER.
This makes samba pass the first part of the samr-lockout test.

This constraint is documented here for the samr server:
http://msdn.microsoft.com/en-us/library/cc245667%28PROT.10%29.aspx
MS-SAMR 3.1.1.6 Attribute Constraints for Originating Updates

and here for the ldap backend:
http://msdn.microsoft.com/en-us/library/cc223462(PROT.10).aspx
MS-ADTS 3.1.1.5.3.2 Constraints

So the check should actually be moved down into the backend,
i.e. under dsdb/samdb/ldb_modules - TODO..

Michael