i2c: mxs: suppress probe-deferral error message

During boot of I2SE Duckbill the kernel log contains a
confusing error:

Failed to request dma

This is caused by i2c-mxs tries to request a not yet available DMA
channel (-EPROBE_DEFER). So suppress this message by using
dev_err_probe().

Signed-off-by: Stefan Wahren <[e-mail]>
Reviewed-by: Fabio Estevam <[e-mail]>
Signed-off-by: Wolfram Sang <[e-mail]>

drivers/i2c/busses/i2c-mxs.c

···
 	/* Setup the DMA */
 	i2c->dmach = dma_request_chan(dev, "rx-tx");
 	if (IS_ERR(i2c->dmach)) {
-		dev_err(dev, "Failed to request dma\n");
-		return PTR_ERR(i2c->dmach);
+		return dev_err_probe(dev, PTR_ERR(i2c->dmach),
+				     "Failed to request dma\n");
 	}
 
 	platform_set_drvdata(pdev, i2c);