TTY: switch tty_buffer_request_room to tty_port

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty pointer in
many call sites. Only tty_port will be needed and hence no more
tty_port_tty_get calls in those paths.

Here we start with tty_buffer_request_room.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/tty_flip.h b/include/linux/tty_flip.h
index 2002344..78207ca 100644
--- a/include/linux/tty_flip.h
+++ b/include/linux/tty_flip.h
@@ -1,7 +1,7 @@
 #ifndef _LINUX_TTY_FLIP_H
 #define _LINUX_TTY_FLIP_H
 
-extern int tty_buffer_request_room(struct tty_struct *tty, size_t size);
+extern int tty_buffer_request_room(struct tty_port *port, size_t size);
 extern int tty_insert_flip_string_flags(struct tty_struct *tty, const unsigned char *chars, const char *flags, size_t size);
 extern int tty_insert_flip_string_fixed_flag(struct tty_struct *tty, const unsigned char *chars, char flag, size_t size);
 extern int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, size_t size);