ARM: imx6: update 1GB DDR3 calibration for DHCOM i.MX6qd PDK

The existing calibration values were found to be incorrect
in comparison to newly determined values.

The new values were generated with the help of 5 boards. They have
been determined with the NXP Utility 'DDR Stress Test (2.9.0)'.

Signed-off-by: Ludwig Zenz <lzenz@dh-electronics.com>