powerpc/srio: Workaround for srio erratrm a004034

Erratum: A-004034
Affects: SRIO

Description: During port initialization, the SRIO port performs
lane synchronization (detecting valid symbols on a lane) and
lane alignment (coordinating multiple lanes to receive valid data
across lanes). Internal errors in lane synchronization and lane
alignment may cause failure to achieve link initialization at
the configured port width.

An SRIO port configured as a 4x port may see one of these scenarios:

1.	One or more lanes fails to achieve lane synchronization.
	Depending on which lanes fail, this may result in downtraining
	from 4x to 1x on lane 0, 4x to 1x on lane R (redundant lane).

2.	The link may fail to achieve lane alignment as a 4x, even
	though all 4 lanes achieve lane synchronization, and downtrain
	to a 1x. An SRIO port configured as a 1x port may fail to complete
	port initialization (PnESCSR[PU] never deasserts) because of
	scenario 1.

Impact: SRIO port may downtrain to 1x, or may fail to complete
link initialization. Once a port completes link initialization
successfully, it will operate normally.

Signed-off-by: Liu Gang <Gang.Liu@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>