We don't emulate the gigabit ethernet part of the chip but the MorphOS
driver accesses these and expects to get some valid looking result
otherwise it hangs. Add some minimal dummy implementation to avoid rhis.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Acked-by: Cédric Le Goater <clg@kaod.org>
Message-ID: <20230605215145.29458746335@zero.eik.bme.hu>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>