edac: mpc85xx improve SDRAM error reporting

Add the ability to detect the specific data line or ECC line which failed
when printing out SDRAM single-bit errors.  An example of a single-bit
SDRAM ECC error is below:

  EDAC MPC85xx MC1: Err Detect Register: 0x80000004
  EDAC MPC85xx MC1: Faulty data bit: 59
  EDAC MPC85xx MC1: Expected Data / ECC:  0x7f80d000_409effa0 / 0x6d
  EDAC MPC85xx MC1: Captured Data / ECC:  0x7780d000_409effa0 / 0x6d
  EDAC MPC85xx MC1: Err addr: 0x00031ca0
  EDAC MPC85xx MC1: PFN: 0x00000031

Knowning which specific data or ECC line caused an error can be useful in
tracking down hardware issues such as improperly terminated signals, loose
pins, etc.

Note that this feature is only currently enabled for 64-bit wide data
buses, 32-bit wide bus support should be added.

I don't have any 32-bit wide systems to test on.  If someone has one and
is willing to give this patch a shot with the check for a 64-bit data bus
removed it would be much appreciated and I can re-submit with both 32 and
64 bit buses supported.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
Signed-off-by: Doug Thompson <dougthompson@xmission.com>
Cc: Kumar Gala <galak@gate.crashing.org>
Cc: Dave Jiang <djiang@mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>