net: axienet: Drop MDIO interrupt registers from ethtools dump

[ Upstream commit c30cb8f0bec69d56e1fbc7fb65bd735c729a69e4 ]

Newer revisions of the IP don't have these registers. Since we don't
really use them, just drop them from the ethtools dump.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 9ff2f816e2aa ("net: axienet: Fix register defines comment description")
Signed-off-by: Sasha Levin <sashal@kernel.org>