JVM IR: Fix types in generated function reference constructor

For references to suspend functions this fixes an IllegalStateException
in the type mapper, which is what the "suspendFunctionMethodReference"
test is about.

compiler/testData/codegen/box/coroutines/suspendFunctionMethodReference.kt

@@ -0,0 +1,11 @@
+// IGNORE_BACKEND: JVM
+// IGNORE_BACKEND_FIR: JVM_IR
+
+fun f(a: suspend () -> Unit): String {
+    val f = a::invoke
+    return "OK"
+}
+
+fun box(): String {
+    return f {}
+}