net: dsa: mv88e6xxx: Fix ATU Miss Violation

Fix a cut/paste error and a typo which results in ATU miss violations
not being reported.

Fixes: 0977644c

 ("net: dsa: mv88e6xxx: Decode ATU problem interrupt")
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>