net: dsa: mv88e6060: use the correct InitReady bit

According to the mv88e6060 datasheet, the InitReady bit position
is 11 and the polarity is inverted.
Use the bit correctly to detect the end of initialization.

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