ttydev: fix pamc_zilog for tty pointer move

Today's linux-next build (powerpc allyesconfig) failed like this:

drivers/serial/pmac_zilog.c: In function 'pmz_receive_chars':
drivers/serial/pmac_zilog.c:245: error: 'struct uart_info' has no member named 'tty'
drivers/serial/pmac_zilog.c:250: error: 'struct uart_info' has no member named 'tty'

I applied the patch below (which builds but may, or may not, be correct).
--
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/serial/pmac_zilog.c

@@ -242,12 +242,12 @@ static struct tty_struct *pmz_receive_chars(struct uart_pmac_port *uap)
 	}
 
 	/* Sanity check, make sure the old bug is no longer happening */
-	if (uap->port.info == NULL || uap->port.info->tty == NULL) {
+	if (uap->port.info == NULL || uap->port.info->port.tty == NULL) {
 		WARN_ON(1);
 		(void)read_zsdata(uap);
 		return NULL;
 	}
-	tty = uap->port.info->tty;
+	tty = uap->port.info->port.tty;
 
 	while (1) {
 		error = 0;