net: dsa: mv88e6xxx: Fix interrupt name for g2 irq

This changes the respective line in /proc/interrupts from

 49:          x          x  mv88e6xxx-g1   7 Edge      mv88e6xxx-g1

to

 49:          x          x  mv88e6xxx-g1   7 Edge      mv88e6xxx-g2

which makes more sense.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>