ddr: altera: Remove unnecessary ODT mode config

There is no point in resetting the ODT setting if the write test
failed, since the code will always retry the calibration and thus
reconfigure the ODT anyway OR the code will fail calibration and
halt.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Chin Liang See <clsee@altera.com>