tty: iuu_phoenix: set termios.

set_termios can now be used for setting the parity and the stopbits. This is
needed to use with cards which use a different parity then the parity used at
start (even).

If the iuu_uart_baud function return an error, we will return the old_termios
instead of the new one.

Signed-off-by: Olivier Bornet <Olivier.Bornet@puck.ch>

This was then revamped to use the various helpers, not copy non-hardware
bits any to add mark/space parity and csize reporting

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>