Change component validator to the correct asset id we're passing in t…

…he API call

app/Http/Controllers/Api/ComponentsController.php

@@ -235,7 +235,7 @@ public function checkout(Request $request, $componentId)
         $this->authorize('checkout', $component);
 
         $validator = Validator::make($request->all(), [
-            'asset_id'          => 'required|exists:assets,id',
+            'assigned_to'          => 'required|exists:assets,id',
             'assigned_qty'      => "required|numeric|min:1|digits_between:1,".$component->numRemaining(),
         ]);