iOS: hide USB button if not supported

Platform/iOS/Display/VMDisplayViewController.m

@@ -46,6 +46,9 @@
     // set up other nibs
     self.removableDrivesViewController = [[VMRemovableDrivesViewController alloc] initWithNibName:@"VMRemovableDrivesView" bundle:nil];
     self.usbDevicesViewController = [[VMUSBDevicesViewController alloc] initWithNibName:@"VMUSBDevicesView" bundle:nil];
+    
+    // hide USB icon if not supported
+    self.usbButton.hidden = self.vm.hasUsbRedirection;
 }
 
 #pragma mark - Properties