recovery: minui: add adf backend

Change-Id: I1ad97b5b62bddbcb1104fa0b4e54415b793a4194
Signed-off-by: Greg Hackmann <ghackmann@google.com>
diff --git a/minui/graphics.h b/minui/graphics.h
index 94b89a5..993e986 100644
--- a/minui/graphics.h
+++ b/minui/graphics.h
@@ -41,6 +41,7 @@
 } minui_backend;
 
 minui_backend* open_fbdev();
+minui_backend* open_adf();
 
 #ifdef __cplusplus
 }