Fix generating Unit-returning bridge for suspend function

#KT-25137 Fixed

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/BridgesBuilding.kt

@@ -261,10 +261,7 @@ private fun Context.buildBridge(startOffset: Int, endOffset: Int,
             }
         }
 
-        if (bridge.returnType.isUnit())
+        +irReturn(delegatingCall)
-            +delegatingCall
-        else
-            +irReturn(delegatingCall)
     }
     return bridge
 }