powerpc/85xx: wait for alignment before resetting SERDES RX lanes (SERDES9)

The work-around for P4080 erratum SERDES9 says that the SERDES receiver
lanes should be reset after the XAUI starts tranmitting alignment signals.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>