um: Use tty_port_operations->destruct

As we setup the SIGWINCH handler in tty_port_operations->activate
it makes sense to tear down it in ->destruct.

Signed-off-by: Richard Weinberger <richard@nod.at>

diff --cc arch/um/drivers/line.c
Simple merge

diff --cc arch/um/drivers/ssl.c
Simple merge

diff --cc arch/um/drivers/stdio_console.c
Simple merge