ASoC: imx-sgtl5000: return E_PROBE_DEFER if ssi/codec not found

If the ssi or codec drivers are not loaded (for instance, because spi or i2c
bus drivers are not loaded), returning -EINVAL will for people to unload and
then reload the module to get sound working. Returning E_PROBE_DEFER will
mitigate this.
Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/fsl/imx-sgtl5000.c

@@ -113,13 +113,13 @@ static int imx_sgtl5000_probe(struct platform_device *pdev)
 	ssi_pdev = of_find_device_by_node(ssi_np);
 	if (!ssi_pdev) {
 		dev_err(&pdev->dev, "failed to find SSI platform device\n");
-		ret = -EINVAL;
+		ret = -EPROBE_DEFER;
 		goto fail;
 	}
 	codec_dev = of_find_i2c_device_by_node(codec_np);
 	if (!codec_dev) {
 		dev_err(&pdev->dev, "failed to find codec platform device\n");
-		return -EINVAL;
+		return -EPROBE_DEFER;
 	}
 
 	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);