ranges: prohibit setting --rid-base with ipa-trust-ad-posix type
    
    We should not allow setting --rid-base for ranges of ipa-trust-ad-posix since we do not perform any RID -> UID/GID mappings for these ranges (objects have UID/GID set in AD). Thus, setting RID base makes no sense.
    
    Since ipaBaseRID is a MUST in ipaTrustedADDomainRange object class, value '0' is allowed and used internally for 'ipa-trust-ad-posix' range type.
    
    No schema change is done.
    
    https://fedorahosted.org/freeipa/ticket/4221
    
    Reviewed-By: Tomas Babej <tbabej@redhat.com>