vt: keyboard, use tty_insert_flip_string in puts_queue

'puts_queue' currently loops over characters and employs the full tty
buffer machinery for every character. Do the buffer allocation only once
and copy all the character at once. This is achieved using
tty_insert_flip_string instead of loop+tty_insert_flip_char.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-17-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/vt/keyboard.c

@@ -324,12 +324,9 @@ static void put_queue(struct vc_data *vc, int ch)
 	tty_schedule_flip(&vc->port);
 }
 
-static void puts_queue(struct vc_data *vc, char *cp)
+static void puts_queue(struct vc_data *vc, const char *cp)
 {
-	while (*cp) {
-		tty_insert_flip_char(&vc->port, *cp, 0);
-		cp++;
-	}
+	tty_insert_flip_string(&vc->port, cp, strlen(cp));
 	tty_schedule_flip(&vc->port);
 }