Fix modifiers generation for companion objects

when language verion is 1.3

 #KT-23002: Fixed

compiler/testData/codegen/box/compatibility/privateCompanionObject.kt

@@ -0,0 +1,12 @@
+// LANGUAGE_VERSION: 1.3
+
+class Test {
+    private companion object {
+        val res = "OK"
+    }
+    fun res() = res
+}
+
+fun box(): String {
+    return Test().res()
+}