karo: tx51: setup SDRAM & NAND control pads from DCD

- Explicitly program the padctl settings for SDRAM and NAND from
  the DCD to ensure correct settings after soft reset.
- Reduce DSE values for SDRAM and NAND control lines for better
  error margins in NAND detection and SDRAM stress test.
- Revert the change of the NFC clock frequency from the previous
  release, as this is not necessary any more with the improved
  pad settings.