powerpc/t104xrdb: Update DDR initialization related settings

Update following DDR related settings for T1040RDB, T1042RDB_PI
-Correct number of chip selects to two as t1040 supports
 two Chip selects.
-Update board_specific_parameters udimm structure with settings
 derived via calibration.
-Update ddr_raw_timing sructure corresponding to DIMM.
-Set ODT to off. Typically on FSL board, ODT is set to 75 ohm,
 but on T104xRDB, on setting this , DDR instability is observed.
 Board-level debugging is in progress.

Verified the updated settings to be working fine with dual-ranked
Micron, MT18KSF51272AZ-1G6 DIMM at data rate 1600MT/s.

Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
Signed-off-by: York Sun <yorksun@freescale.com>