serial: Set baudrate on boot
Currently, the baud rate is never set on boot. This works ok when a previous
bootloader has configured the baudrate properly, or when the baudrate is set to
a reasonable default in the serial driver's probe(). However, when this is not
the case, we could be using a different baud rate than what was configured.
Signed-off-by: Sean Anderson <seanga2@gmail.com>