FIR2IR fix enum special methods generation

compiler/testData/codegen/box/enum/javaEnumValueOf.kt

@@ -0,0 +1,14 @@
+// TARGET_BACKEND: JVM
+// FILE: E.java
+public enum E {
+    OK();
+    public static String valueOf(E x) {
+        return x.toString();
+    }
+}
+
+// FILE: test.kt
+
+// check that both 'valueOf(String): E' and 'valueOf(E): String' are invoked correctly
+fun box() =
+    E.valueOf(E.valueOf("OK"))