cifs: fix parsing of symbolic link error response

RHBZ: 1672539

In smb2_query_symlink(), if we are parsing the error buffer but it is not something
we recognize as a symlink we should return -EINVAL and not -ENOENT.
I.e. the entry does exist, it is just not something we recognize.

Additionally, add check to verify that that the errortag and the reparsetag all make sense.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Acked-by: Paulo Alcantara <palcantara@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>