Merge branch '2020-06-26-more-Kconfig-migration' into next

- Bring in the first pass at cleaning up config headers that reference
  symbols that already have Kconfig symbols.
- In order to do that, bring in the small series that adds
  CONFIG_SPL_DM_SPI_FLASH and makes more use of CONFIG_$(SPL_TPL_)DM_SPI
  in order to allow for disabling those features in SPL stuff but using
  them in full U-Boot