mpc83xx: Update DIMM data bus width test to support 40-bit width

32-bit wide ECC memory modules report 40-bit width.
Changed the DIMM data bus width test to 'less than 64' instead of 'equal 32'.

Signed-off-by: Lee Nipper <lee.nipper@freescale.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>