Condition of 'if' expression is constant: report enum entries comparison

#KT-28803 Fixed

idea/testData/inspectionsLocal/constantConditionIf/enumEntryNotEq.kt

@@ -0,0 +1,10 @@
+// PROBLEM: Condition is always 'false'
+enum class Enum {
+    A, B, C
+}
+
+fun foo(x: Int) {}
+
+fun bar() {
+    foo(if (<caret>Enum.A != Enum.A) 1 else 2)
+}