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/synclinkmp.c b/drivers/tty/synclinkmp.c
index 419f58f..e4a2904 100644
--- a/drivers/tty/synclinkmp.c
+++ b/drivers/tty/synclinkmp.c
@@ -2167,7 +2167,6 @@
 {
 	u16 status;
 	unsigned char DataByte;
- 	struct tty_struct *tty = info->port.tty;
  	struct	mgsl_icount *icount = &info->icount;
 
 	if ( debug_level >= DEBUG_LEVEL_ISR )
@@ -2225,8 +2224,7 @@
 			icount->frame,icount->overrun);
 	}
 
-	if ( tty )
-		tty_flip_buffer_push(tty);
+	tty_flip_buffer_push(&info->port);
 }
 
 static void isr_txeom(SLMP_INFO * info, unsigned char status)