net: dsa: mv88e6xxx: Fix off by in one in mv88e6185_phylink_get_caps()

The <= ARRAY_SIZE() needs to be < ARRAY_SIZE() to prevent an out of
bounds error.

Fixes: d4ebf12b ("net: dsa: mv88e6xxx: populate supported_interfaces and mac_capabilities")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>