drivers: iio: frequency: ad7192: Fix failed clocks warning

This patch verifies that the return message from ad9172_get_clks is
different from EPROBE_DEFER, this way the dev_err message is not thrown in
case of a retry.

Signed-off-by: Mircea Caprioru <mircea.caprioru@analog.com>

drivers/iio/frequency/ad9172.c

@@ -886,7 +886,8 @@ static int ad9172_probe(struct spi_device *spi)
 
 	ret = ad9172_get_clks(conv);
 	if (ret < 0) {
-		dev_err(&spi->dev, "Failed to get clocks\n");
+		if (ret != -EPROBE_DEFER)
+			dev_err(&spi->dev, "Failed to get clocks\n");
 		goto out;
 	}