[ Upstream commit ea89098ef9a574bceca00d3b5df14aaf0b3f9ccf ]

The 6390 copper ports have an errata which require poking magic values
into undocumented magic registers and then performing a software
reset.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>