mx7ulp_evk: Update LPDDR3 script

Update LPDDR3 script with the changes below:
  -Update the precharge command to CMD=01 at the DDR initialization phase
  -remove unimplemented registers
   Write data bit delay --refer to the DDR_TRIM bits in
   IOMUXC1_DDR_SW_PAD_CTL_PAD_DDRn

Test:
  One EVK board passes overnight stress test.

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>