mpc85xx: Adding more registers and options

This patch exposes more registers which can be used by the DDR drivers or
interactive debugging. U-boot doesn't use all the registers in DDRC.
When advanced tuning is required, writing to those registers is needed.

Add writing to cdr1, cdr2, err_disable, err_int_en and debug registers
Add options to override rcw, address parity to RDIMMs.
Use array for debug registers.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>