board: bsh: imx6ulz_smm_m2: Match SPL DDR settings to DCD table

board: bsh: imx6ulz_smm_m2: Match SPL DDR settings to DCD table

When using SPL on i.mx6 we frequently notice some DDR initialization
mismatches between the SPL code and the non-SPL code.

As the non-SPL code have been tested for long time and proves to be
reliable, let's configure the DDR in the exact same way as the non-SPL
case.

The idea is simple: just use the DCD table and write directly to the DDR
registers.

Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>