ASoC: rsnd: dma.c: tidyup rsnd_dma_probe()

This patch tidyups rsnd_dma_probe(), but there is no effect.

This is prepare for Gen4 support.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87r0va5elq.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sh/rcar/dma.c

@@ -885,13 +885,18 @@ int rsnd_dma_probe(struct rsnd_priv *priv)
 	/*
 	 * for Gen2 or later
 	 */
-	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "audmapp");
 	dmac = devm_kzalloc(dev, sizeof(*dmac), GFP_KERNEL);
-	if (!dmac || !res) {
+	if (!dmac) {
 		dev_err(dev, "dma allocate failed\n");
 		return 0; /* it will be PIO mode */
 	}
 
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "audmapp");
+	if (!res) {
+		dev_err(dev, "lack of audmapp in DT\n");
+		return 0; /* it will be PIO mode */
+	}
+
 	dmac->dmapp_num = 0;
 	dmac->ppres  = res->start;
 	dmac->ppbase = devm_ioremap_resource(dev, res);