[Rust] removed unused method parameter

Author: Michael Ward

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/rust/RustGenerator.java

@@ -1271,7 +1271,7 @@ private static void generateEnum(
         generateFromEnumForPrimitive(enumRustName, primitiveType, messageBody, writer);
 
         // FromStr impl
-        generateFromStrImplForEnum(enumRustName, primitiveType, messageBody, writer);
+        generateFromStrImplForEnum(enumRustName, messageBody, writer);
 
         // Display impl
         generateDisplayImplForEnum(enumRustName, primitiveType, messageBody, writer);
@@ -1333,7 +1333,6 @@ private static void generateFromEnumForPrimitive(
 
     private static void generateFromStrImplForEnum(
         final String enumRustName,
-        final String primitiveType,
         final List<Token> messageBody,
         final Appendable writer) throws IOException
     {