Update TANARO U-Boot to 2020.04: Update Defconfig

update TANARO defconfig to compile and work for U-Boot 2020.04.
This patch is the first version, that compiles without errors and boots
up with FnG-System via uuu completely.

No further tests done, yet, i.e. not flashed to eMMC, not booted from
eMMC, no bootselect tests, etc.