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/sn_console.c b/drivers/tty/serial/sn_console.c
index 283232c..f51ffdc 100644
--- a/drivers/tty/serial/sn_console.c
+++ b/drivers/tty/serial/sn_console.c
@@ -459,7 +459,6 @@
 {
 	struct tty_port *tport = NULL;
 	int ch;
-	struct tty_struct *tty;
 
 	if (!port) {
 		printk(KERN_ERR "sn_receive_chars - port NULL so can't receive\n");
@@ -474,11 +473,6 @@
 	if (port->sc_port.state) {
 		/* The serial_core stuffs are initialized, use them */
 		tport = &port->sc_port.state->port;
-		tty = tport->tty;
-	}
-	else {
-		/* Not registered yet - can't pass to tty layer.  */
-		tty = NULL;
 	}
 
 	while (port->sc_ops->sal_input_pending()) {
@@ -518,15 +512,15 @@
 #endif /* CONFIG_MAGIC_SYSRQ */
 
 		/* record the character to pass up to the tty layer */
-		if (tty) {
+		if (tport) {
 			if (tty_insert_flip_char(tport, ch, TTY_NORMAL) == 0)
 				break;
 		}
 		port->sc_port.icount.rx++;
 	}
 
-	if (tty)
-		tty_flip_buffer_push(tty);
+	if (tport)
+		tty_flip_buffer_push(tport);
 }
 
 /**