net: dsa: mv88e6xxx: set ethtool regs version

Currently the ethtool_regs version is set to 0 for all DSA drivers.

Use this field to store the chip ID to simplify the pretty dump of
any interfaces registered by the "dsa" driver.
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -1124,7 +1124,7 @@ static void mv88e6xxx_get_regs(struct dsa_switch *ds, int port,
 	u16 *p = _p;
 	int i;
 
-	regs->version = 0;
+	regs->version = chip->info->prod_num;
 
 	memset(p, 0xff, 32 * sizeof(u16));