powerpc/mpc85xx: Skip zero values for DDR debug registers

Some debug registers have non-zero default out of reset. If software is
not setting debug registers, skip writing to them to avoid unnecessary
overriding.

Also add debug messages for workarounds and debug registers.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>
1 file changed