TTY: simserial/amiserial, use one instance of other members

This means:
* close_delay
* closing_wait
* line
* port
* xmit_fifo_size

This actually fixes a bug in amiserial. It initializes one and uses
the other of the close delays. Yes, duplicating structure members is
evil.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>