FDDI: defza: Fix SPDX annotation

The SPDX annotation for this driver does not match the license text,
which specifies GNU GPL 2 or later.  Make the two match by correcting
the SPDX tag.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>