The OpenOCD STM32-specific configuration was included into the common
configuration, which was then used in board files. Follow nRF5
convention instead: use manufacturer-specific config in boards.
Also due to the fact that the include of STM32-specific config was
placed *after* board_finalize_runner_args() it didn't really work
anyways.
Signed-off-by: Marek Metelski <marek@metelski.dev>