ASoC: davinci-mcasp: check memory allocation failure

Check memory allocation failures and return -ENOMEM in such cases, as
already done above for another memory allocation.

This avoids NULL pointers dereference.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/davinci/davinci-mcasp.c

@@ -1851,6 +1851,10 @@ static int davinci_mcasp_probe(struct platform_device *pdev)
 	mcasp->context.xrsr_regs = devm_kzalloc(&pdev->dev,
 					sizeof(u32) * mcasp->num_serializer,
 					GFP_KERNEL);
+	if (!mcasp->context.xrsr_regs) {
+		ret = -ENOMEM;
+		goto err;
+	}
 #endif
 	mcasp->serial_dir = pdata->serial_dir;
 	mcasp->version = pdata->version;