spi: axi-spi-engine: simplify driver data allocation

This simplifies the private data allocation in the AXI SPI Engine driver
by making use of the feature built into the spi_alloc_host() function
instead of doing it manually.
Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20231117-axi-spi-engine-series-1-v1-3-cc59db999b87@baylibre.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-axi-spi-engine.c

@@ -473,15 +473,11 @@ static int spi_engine_probe(struct platform_device *pdev)
 	if (irq < 0)
 		return irq;
 
-	spi_engine = devm_kzalloc(&pdev->dev, sizeof(*spi_engine), GFP_KERNEL);
-	if (!spi_engine)
-		return -ENOMEM;
-
-	host = spi_alloc_host(&pdev->dev, 0);
+	host = spi_alloc_host(&pdev->dev, sizeof(*spi_engine));
 	if (!host)
 		return -ENOMEM;
 
-	spi_controller_set_devdata(host, spi_engine);
+	spi_engine = spi_controller_get_devdata(host);
 
 	spin_lock_init(&spi_engine->lock);