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: 31557f0f ("mlxsw: Introduce Mellanox SwitchX-2 ASIC support")
Signed-off-by: NYotam Gigi <yotamg@mellanox.com>
Acked-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>