drm: xlnx: zynqmp_dpsub: Add NULL check in zynqmp_audio_init

devm_kasprintf() calls can return null pointers on failure.
But some return values were not checked in zynqmp_audio_init().

Add NULL check in zynqmp_audio_init(), avoid referencing null
pointers in the subsequent code.

Fixes: 3ec5c15 ("drm: xlnx: zynqmp_dpsub: Add DP audio support")
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Charles Han <hanchunchao@inspur.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250211102049.6468-1-hanchunchao@inspur.com

Author: Charles Han

drivers/gpu/drm/xlnx/zynqmp_dp_audio.c

@@ -323,12 +323,16 @@ int zynqmp_audio_init(struct zynqmp_dpsub *dpsub)
 
 	audio->dai_name = devm_kasprintf(dev, GFP_KERNEL,
 					 "%s-dai", dev_name(dev));
+	if (!audio->dai_name)
+		return -ENOMEM;
 
 	for (unsigned int i = 0; i < ZYNQMP_NUM_PCMS; ++i) {
 		audio->link_names[i] = devm_kasprintf(dev, GFP_KERNEL,
 						      "%s-dp-%u", dev_name(dev), i);
 		audio->pcm_names[i] = devm_kasprintf(dev, GFP_KERNEL,
 						     "%s-pcm-%u", dev_name(dev), i);
+		if (!audio->link_names[i] || !audio->pcm_names[i])
+			return -ENOMEM;
 	}
 
 	audio->base = devm_platform_ioremap_resource_byname(pdev, "aud");