net: dsa: mv88e6060: use the correct bit shift for mac0

According to the mv88e6060 datasheet, the first mac byte must
be at position 9 instead of 8 since the bit 8 is used to select
if the mac address must differ for each port for Pause frames.
Use the correct shift and set the same mac address for all port.

Acked-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>