The numeric constants in the switch statements are replaced by #defines
added to the common ddr_spd.h header.  This dramatically improves the
readability of the switch statments.

In addition, a few of the longer lines were cleaned up, and the DDR2
type for an SO-RDIMM module was added to the DDR2 switch statement.
Signed-off-by: NKyle Moffett <Kyle.D.Moffett@boeing.com>
Cc: Andy Fleming <afleming@gmail.com>
Cc: Kim Phillips <kim.phillips@freescale.com>
Acked-by: NYork Sun <yorksun@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

Enabled registered DIMMs using data from SPD. RDIMMs have registers
which need to be configured before using. The register configuration
words are stored in SPD byte 60~116 (JEDEC standard No.21-C). Software
should read those RCWs and put into DDR controller before initialization.
Signed-off-by: NYork Sun <yorksun@freescale.com>

- support mirrored DIMMs, not support register DIMMs
- test passed on P2020DS board with MT9JSF12872AY-1G1D1
- test passed on MPC8569MDS board with MT8JSF12864HY-1G1D1
Signed-off-by: NDave Liu <daveliu@freescale.com>
Signed-off-by: NTravis Wheatley <travis.wheatley@freescale.com>

Also adds helper functions for DDR1/2 to verify the checksum.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>