tty: phase out of ioctl file pointer for tty3270 as well

The patch "tty: now phase out the ioctl file pointer for good" missed
the tty3270 driver. This is the missing piece.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>