This PR adds support for the Challenger 840 BLE board.
It also adds the possibility to add a board specific initialization function (extern_board_init()) to the board specific files. This is done by having a weak declared function in boards.c that can be overridden by the board specific files.
This PR adds support for the Challenger 840 BLE board. It also adds the possibility to add a board specific initialization function (extern_board_init()) to the board specific files. This is done by having a weak declared function in boards.c that can be overridden by the board specific files.