TTY: tty_io, remove buffer re-assignments

TTY buffer head and tail are initialized in tty_buffer_init. No need
to do it once again in initialize_tty_struct where tty_buffer_init is
called.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/tty_io.c

@@ -2933,7 +2933,6 @@ void initialize_tty_struct(struct tty_struct *tty,
 	tty->session = NULL;
 	tty->pgrp = NULL;
 	tty->overrun_time = jiffies;
-	tty->buf.head = tty->buf.tail = NULL;
 	tty_buffer_init(tty);
 	mutex_init(&tty->termios_mutex);
 	mutex_init(&tty->ldisc_mutex);