Revert "Move error_code.h into otautil."

This reverts commit 623fe7e701d5d0fb17082d1ced14498af1b44e5b.

Reason for revert: Need to address device-specific modules.

Change-Id: Ib7a4191e7f193dfff49b02d3de76dda856800251
diff --git a/edify/expr.h b/edify/expr.h
index f2a4d6d..4838d20 100644
--- a/edify/expr.h
+++ b/edify/expr.h
@@ -23,7 +23,7 @@
 #include <string>
 #include <vector>
 
-#include "otautil/error_code.h"
+#include "error_code.h"
 
 struct State {
     State(const std::string& script, void* cookie);