Fix mapping of nullable generic underlying types of inline classes

#KT-32162 Fixed

compiler/testData/codegen/box/inlineClasses/resultGeneric2.kt

@@ -0,0 +1,19 @@
+// IGNORE_BACKEND: WASM, JS_IR
+// IGNORE_BACKEND: ANDROID
+// IGNORE_BACKEND: NATIVE
+// ALLOW_KOTLIN_PACKAGE
+// WITH_STDLIB
+// WORKS_WHEN_VALUE_CLASS
+// LANGUAGE: +ValueClasses, +GenericInlineClassParameter
+
+// FILE: result.kt
+package kotlin
+
+OPTIONAL_JVM_INLINE_ANNOTATION
+value class Result<T: Any>(val value: T?)
+
+// FILE: box.kt
+
+fun box(): String {
+    return Result("OK").value!!
+}