USB: serial: ark3116.c: Mixed fixups

o	Don't parse the cflag for baud rates, its not valid to do so
	any more and this driver got it wrong anyway
o	Don't do clever termios change checks in drivers and get them
	wrong (arguably we should do some smart ones in the tty core but
	stty to change nothing is *not* a common or critical path

I don't have the hardware so if you can test this carefully please do. I
thought fixing it up this far was better than marking it and other bits of
USB serial && BROKEN

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>