[nrf fromtree] boards: Add nRF52840DK bare variant#3007

tomchy wants to merge 1 commit intonrfconnect:mainnrfconnect/sdk-zephyr:mainfrom

tomchy:feature/sysbuild/NCSDK-NONE_Introduce_dongle_bare_varianttomchy/sdk-zephyr:feature/sysbuild/NCSDK-NONE_Introduce_dongle_bare_variantCopy head branch name to clipboard