iio: adc: cc10001: Add delay before setting START bit

According to hardware team there should be some delay after
setting channel number, start mode and before setting START.
Add a one microsecond delay for this purpose.

Fixes: 1664f6a ("iio: adc: Cosmic Circuits 10001 ADC driver")
Signed-off-by: Naidu Tellapati <naidu.tellapati@imgtec.com>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/cc10001_adc.c

@@ -100,6 +100,7 @@ static void cc10001_adc_start(struct cc10001_adc_device *adc_dev,
 	val = (channel & CC10001_ADC_CH_MASK) | CC10001_ADC_MODE_SINGLE_CONV;
 	cc10001_adc_write_reg(adc_dev, CC10001_ADC_CONFIG, val);
 
+	udelay(1);
 	val = cc10001_adc_read_reg(adc_dev, CC10001_ADC_CONFIG);
 	val = val | CC10001_ADC_START_CONV;
 	cc10001_adc_write_reg(adc_dev, CC10001_ADC_CONFIG, val);