MLK-13407: mx6qarm2: mt128x64mx3 2: add init pre charge all command

MLK-13407: mx6qarm2: mt128x64mx3 2: add init pre charge all command

- Adjust ZQ delay for MMDC clock frequency at 400MHz
- Precharge all commands per JEDEC
  The memory controller may optionally issue a Precharge-All command
  prior to the MRW Reset command, this is strongly recommended to ensure
  a robust DRAM initialization

DDR Calibration script:
http://sw-stash.freescale.net/projects/IMX/repos/ddr-scripts-rel/commits/a72e010a1fd8c7fe0fda7bdc4d058c478e94c3da

Signed-off-by: Adrian Alonso <adrian.alonso@nxp.com>
(cherry picked from commit 03cc626df73d6c2bb36daf280b1cd43170c298a0)