qcam: viewfinder: Move multi-planar check into viewfinder

The lack of support for multiplanar buffers comes from the viewfinder.
Move the corresponding check from MainWindow.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/qcam/main_window.cpp

@@ -524,14 +524,9 @@ void MainWindow::processCapture()
 	queueRequest(buffer);
 }
 
-int MainWindow::display(FrameBuffer *buffer)
+void MainWindow::display(FrameBuffer *buffer)
 {
-	if (buffer->planes().size() != 1)
-		return -EINVAL;
-
 	viewfinder_->display(buffer, &mappedBuffers_[buffer]);
-
-	return 0;
 }
 
 void MainWindow::queueRequest(FrameBuffer *buffer)