When changing the link between 100Mbps and 1Gbps in SGMII mode it was
found out that the link would stop working.  The issue is that ECNTRL[R100]
needs to be cleared when in 1Gbps mode.  Older reference manuals didn't
require the explicitly clearing but has since been found it that it is
needed.
Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Andy Fleming <afleming@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>