JVM IR: fix behavior of Enum.entries for unlowered enums

#KT-57671 Fixed

compiler/testData/codegen/bytecodeText/enum/kt57671_1.kt

@@ -0,0 +1,13 @@
+// TARGET_BACKEND: JVM_IR
+// FILE: 1.kt
+
+enum class E
+
+// FILE: 2.kt
+
+@OptIn(ExperimentalStdlibApi::class)
+fun test() {
+    E.entries
+}
+
+// 0 EntriesMappings

compiler/testData/codegen/bytecodeText/enum/kt57671_2.kt

@@ -0,0 +1,13 @@
+// TARGET_BACKEND: JVM_IR
+// FILE: 1.kt
+
+@OptIn(ExperimentalStdlibApi::class)
+fun test() {
+    E.entries
+}
+
+// FILE: 2.kt
+
+enum class E
+
+// 0 EntriesMappings