LeakingThisInspection: fix false positives for enum class

#KT-25905 Fixed

idea/testData/inspectionsLocal/leakingThis/enumEntryHasOverriddenMember7.kt

@@ -0,0 +1,14 @@
+// PROBLEM: none
+// FIX: none
+enum class Foo : Bar {
+    ONE {
+        override fun x() = 1
+    };
+
+    val double = <caret>x(2)
+}
+
+interface Bar {
+    fun x(): Int = 42
+    fun x(i: Int): Int = 24
+}