Merge https://gitlab.denx.de/u-boot/custodians/u-boot-marvell

- Armada 8k: Add NAND support via PXA3xx NAND driver (Baruch)
- Armada 8k: Use ATF serdes init instead of the "old" U-Boot version
  (Baruch)
- Minor update to Octeon TX/TX2 defconfig (Stefan)