Fixed KT-4431 Override/implement val: generate getter instead of initializer

#KT-4431 Fixed

idea/testData/codeInsight/overrideImplement/complexMultiOverride.kt.after

@@ -21,7 +21,9 @@ class C : Base<String, C, Unit>() {
         return super<Base>.hashCode()
     }
 
-    override val method: (String?) -> String = ?
+    override val method: (String?) -> String
+        get() = ?
+
     override fun toString(): String {
         return super<Base>.toString()
     }