net: usb: asix: ax88772_bind: use devm_kzalloc() instead of kzalloc()

Make resource management easier, use devm_kzalloc().

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>