TTY: use tty_port_register_device

Currently we have no way to assign tty->port while performing tty
installation. There are two ways to provide the link tty_struct =>
tty_port. Either by calling tty_port_install from tty->ops->install or
tty_port_register_device called instead of tty_register_device when
the device is being set up after connected.

In this patch we modify most of the drivers to do the latter. When the
drivers use tty_register_device and we have tty_port already, we
switch to tty_port_register_device. So we have the tty_struct =>
tty_port link for free for those.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index bbaf2c5..457475f 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -409,7 +409,8 @@
 		line->valid = 1;
 		err = parse_chan_pair(new, line, n, opts, error_out);
 		if (!err) {
-			struct device *d = tty_register_device(driver, n, NULL);
+			struct device *d = tty_port_register_device(&line->port,
+					driver, n, NULL);
 			if (IS_ERR(d)) {
 				*error_out = "Failed to register device";
 				err = PTR_ERR(d);