protocol: Add create_read_window

Change-Id: I82e9e69861163fb1ae35313fcfee37e03be69f65
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/mbox.h b/mbox.h
index 5fd074b..3676825 100644
--- a/mbox.h
+++ b/mbox.h
@@ -133,6 +133,7 @@
 };
 
 struct mbox_context;
+
 typedef int (*mboxd_mbox_handler)(struct mbox_context *, union mbox_regs *,
 				  struct mbox_msg *);