[hci] Split out msg() and alert() from settings UI code

The msg() and alert() functions currently defined in settings_ui.c
provide a general-purpose facility for printing messages centred on
the screen.

Split this out to a separate file to allow for reuse by the form
presentation code.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/message.h

@@ -0,0 +1,16 @@
+#ifndef _IPXE_MESSAGE_H
+#define _IPXE_MESSAGE_H
+
+/** @file
+ *
+ * Message printing
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+extern void msg ( unsigned int row, const char *fmt, ... );
+extern void clearmsg ( unsigned int row );
+extern void alert ( unsigned int row, const char *fmt, ... );
+
+#endif /* _IPXE_MESSAGE_H */