net: mvneta: enable NETIF_F_RXCSUM by default

The code and HW supports NETIF_F_RXCSUM, so let's enable it by default.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Reviewed-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>