Merge branch '2021-08-31-kconfig-migrations-part2' into next

- Further CONFIG to Kconfig migrations
  - Some DDR related symbols
  - CONFIG_SYS_LOAD_ADDR moved, loadaddr always set in environment now.
  - Finish MX7D, convert IMX_CONFIG
  - Some RAMBOOT related options
  - L1 cache size converted and named consistently for all arches.  A
    further follow-up to rename things for even better clarity is welcome.
  - CONFIG_SKIP_LOWLEVEL_INIT, CONFIG_SYS_MALLOC_LEN