Fix warning on uninitialized buftype

Pointed out by coverity analyzer.  resp_buftype is
not initialized in one path which can rarely log
a spurious warning (buf is null so there will
not be a problem with freeing data, but if buf_type
were randomly set to wrong value could log a warning)

Reported by Coverity (CID 1269144)

Signed-off-by: Steve French <smfrench@gmail.com>
Acked-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Acked-by: Sachin Prabhu <sprabhu@redhat.com>
Reviewed-by: Jeff Layton <jlayton@poochiereds.net>