commit ca4383a3 upstream.

Add missing error handling when registering the tty device at port
probe. This avoids trying to remove an uninitialised character device
when the port device is removed.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Greg Kroah-Hartman <greg@kroah.com>
[bwh: Backported to 3.2:
 - Adjust context
 - No need to clean up autopm]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>