[Serial] Add 256000 and 460800 serial baudrates
Used for Mavlink over HIL USART, to allow using the same baudrate as the one used by HIL. Also one more option can't hurt :)
Depends on: !29 (merged)
Used for Mavlink over HIL USART, to allow using the same baudrate as the one used by HIL. Also one more option can't hurt :)
Depends on: !29 (merged)