imx: kontron-sl-mx8mm: Use new LPDDR4 config parameters

These parameters are needed for stable performance on new hardware
with Nanya LPDDR4 chips.

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Fabio Estevam <festevam@denx.de>
2 files changed