net: dsa: mv88e6131: drop VLAN Ethertype setup

The 6131 switch models have a Core Tag Type register. Their setup code
is setting it to 0x8100, which is the reset default.

Drop this specific part which is correctly configured on reset anyway.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6131.c

@@ -65,11 +65,6 @@ static int mv88e6131_setup_global(struct dsa_switch *ds)
 	int ret;
 	u32 reg;
 
-	/* Set the VLAN ethertype to 0x8100. */
-	ret = mv88e6xxx_reg_write(ps, REG_GLOBAL, GLOBAL_CORE_TAG_TYPE, 0x8100);
-	if (ret)
-		return ret;
-
 	/* Disable ARP mirroring, and configure the upstream port as
 	 * the port to which ingress and egress monitor frames are to
 	 * be sent.