serial: 8250_fintek: Add F81216 Support

Fintek F81216 is a LPC to 4 UARTs device. It's the F81216 series but
support less functional than F81216AD/F81216H

The following list is brief descriptions of F81216 series:

F81216H (0105)
	9Bit/High baud rate(not implements with mainline)
	RS485, 128Bytes FIFO (implemented)

F81216AD (0216)
	9Bit(not implements with mainline)
	RS485(implemented)

F81216 (0208)
	basically 16550A

Suggested-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>