tty_ioctl(): start taking TIOC[SG]SERIAL into separate methods

->set_serial() and ->get_serial() resp., both taking tty and
a kernel pointer to serial_struct.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 71dbc89..3584462 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -249,6 +249,7 @@
 struct tty_struct;
 struct tty_driver;
 struct serial_icounter_struct;
+struct serial_struct;
 
 struct tty_operations {
 	struct tty_struct * (*lookup)(struct tty_driver *driver,
@@ -287,6 +288,8 @@ struct tty_operations {
 	int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
 	int (*get_icount)(struct tty_struct *tty,
 				struct serial_icounter_struct *icount);
+	int  (*get_serial)(struct tty_struct *tty, struct serial_struct *p);
+	int  (*set_serial)(struct tty_struct *tty, struct serial_struct *p);
 	void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);
 #ifdef CONFIG_CONSOLE_POLL
 	int (*poll_init)(struct tty_driver *driver, int line, char *options);