add support for generic register access using bfgen

Signed-off-by: Julien Peeters <contact@julienpeeters.net>
port stm32 early console to generic register access

Signed-off-by: Julien Peeters <contact@julienpeeters.net>
add support for arguments to kermit script

Signed-off-by: Julien Peeters <contact@julienpeeters.net>