TTY: switch tty_flip_buffer_push

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.

IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.

Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/dz.c b/drivers/tty/serial/dz.c
index 6491b86..2f2b2e5 100644
--- a/drivers/tty/serial/dz.c
+++ b/drivers/tty/serial/dz.c
@@ -187,7 +187,6 @@
 {
 	struct uart_port *uport;
 	struct dz_port *dport = &mux->dport[0];
-	struct tty_struct *tty = NULL;
 	struct uart_icount *icount;
 	int lines_rx[DZ_NB_PORT] = { [0 ... DZ_NB_PORT - 1] = 0 };
 	unsigned char ch, flag;
@@ -197,7 +196,6 @@
 	while ((status = dz_in(dport, DZ_RBUF)) & DZ_DVAL) {
 		dport = &mux->dport[LINE(status)];
 		uport = &dport->port;
-		tty = uport->state->port.tty;	/* point to the proper dev */
 
 		ch = UCHAR(status);		/* grab the char */
 		flag = TTY_NORMAL;
@@ -249,7 +247,7 @@
 	}
 	for (i = 0; i < DZ_NB_PORT; i++)
 		if (lines_rx[i])
-			tty_flip_buffer_push(mux->dport[i].port.state->port.tty);
+			tty_flip_buffer_push(&mux->dport[i].port.state->port);
 }
 
 /*