iio: frequency: ad9523: Increase sleep time in ad9523_store_eeprom

This patch increases sleep time in ad9523_store_eeprom to 20ms since
it isn't timing critical. It fixes the following checkpatch.pl warning:
WARNING: msleep < 20ms can sleep for up to 20ms
Signed-off-by: Roberta Dobrescu <roberta.dobrescu@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/frequency/ad9523.c

@@ -445,7 +445,7 @@ static int ad9523_store_eeprom(struct iio_dev *indio_dev)
 
 	tmp = 4;
 	do {
-		msleep(16);
+		msleep(20);
 		ret = ad9523_read(indio_dev,
 				  AD9523_EEPROM_DATA_XFER_STATUS);
 		if (ret < 0)