"serial_" API is designed for UART debug and "serial_stub_" API
is designed for stdio device(e.g. keyboard, video, lcd...).
We need new API for normal serial device, e.g. a UART working
with other peripheral device.
Signed-off-by: Joseph Chen <chenjh@rock-chips.com>
Change-Id: Ifc2cb2ca9c1d4a395e89ceb5e059ec05a07b1967