mlxsw: switchx2: Fix misuse of hard_header_len

In order to specify that the mlxsw switchx2 driver needs additional
headroom for packets, there have been use of the hard_header_len field of
the netdevice struct.

This commit changes that to use needed_headroom instead, as this is the
correct way to do that.

Fixes: 31557f0f9755 ("mlxsw: Introduce Mellanox SwitchX-2 ASIC support")
Signed-off-by: Yotam Gigi <yotamg@mellanox.com>
Acked-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/switchx2.c

@@ -997,7 +997,7 @@ static int mlxsw_sx_port_create(struct mlxsw_sx *mlxsw_sx, u8 local_port)
 	/* Each packet needs to have a Tx header (metadata) on top all other
 	 * headers.
 	 */
-	dev->hard_header_len += MLXSW_TXHDR_LEN;
+	dev->needed_headroom = MLXSW_TXHDR_LEN;
 
 	err = mlxsw_sx_port_module_check(mlxsw_sx_port, &usable);
 	if (err) {