85xx: Add CPU 2 errata workaround to all 8548 boards

All mpc8548-based boards should implement the suggested workaround
to CPU 2 errata. Without the workaround, its possible for the
8548's core to hang while executing a msync or mbar 0 instruction
and a snoopable transaction from an I/O master tagged to make
quick forward progress is present.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
Acked-by: Andy Fleming <afleming@freescale.com>