main: Convert serial_putc() to serial_puts()
main: Convert serial_putc() to serial_puts()

This fixes printing '\r' when '\n' is printed.

Signed-off-by: Sean Cross <dd28e116ed3e781f3ae781acae9fb18383f35c2f@kosagi.com>

urjaman/fernly,urjaman/fernly,pfalcon/fernly,mandl/fernly,mandl/fernly,urjaman/fernly,xobs/fernly,pfalcon/fernly,mandl/fernly,xobs/fernly