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/icom.c b/drivers/tty/serial/icom.c
index 54903ee..bc9e6b01 100644
--- a/drivers/tty/serial/icom.c
+++ b/drivers/tty/serial/icom.c
@@ -735,7 +735,6 @@
 {
 	short int count, rcv_buff;
 	struct tty_port *port = &icom_port->uart_port.state->port;
-	struct tty_struct *tty = port->tty;
 	unsigned short int status;
 	struct uart_icount *icount;
 	unsigned long offset;
@@ -835,7 +834,7 @@
 		status = cpu_to_le16(icom_port->statStg->rcv[rcv_buff].flags);
 	}
 	icom_port->next_rcv = rcv_buff;
-	tty_flip_buffer_push(tty);
+	tty_flip_buffer_push(port);
 }
 
 static void process_interrupt(u16 port_int_reg,