Move FQName to libhidl-gen-util.

This will allow other libraries to process FQNames, namely libhidl.

Test: compiles
Change-Id: I015a69e016c5cef37f42e02b54c22663315e3676
diff --git a/AST.h b/AST.h
index a7f08b2..d89f681 100644
--- a/AST.h
+++ b/AST.h
@@ -19,12 +19,12 @@
 #define AST_H_
 
 #include <android-base/macros.h>
+#include <hidl-util/FQName.h>
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
-#include "FQName.h"
 #include "Type.h"
 
 namespace android {