iio: stmpe-adc: Use wait_for_completion_timeout

Use wait_for_completion_timeout instead of
wait_for_completion_interuptible_timeout.

The interruptible variant gets constantly interrupted if a user
program is compiled with the -pg option.
The killable variant was not used due to the fact that a second
program, reading on this device, that gets killed is then also killing
that wait.
Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/stmpe-adc.c

@@ -77,15 +77,11 @@ static int stmpe_read_voltage(struct stmpe_adc *info,
 	stmpe_reg_write(info->stmpe, STMPE_REG_ADC_CAPT,
 			STMPE_ADC_CH(info->channel));
 
-	ret = wait_for_completion_interruptible_timeout
-		(&info->completion, STMPE_ADC_TIMEOUT);
+	ret = wait_for_completion_timeout(&info->completion, STMPE_ADC_TIMEOUT);
 
 	if (ret <= 0) {
 		mutex_unlock(&info->lock);
-		if (ret == 0)
-			return -ETIMEDOUT;
-		else
-			return ret;
+		return -ETIMEDOUT;
 	}
 
 	*val = info->value;
@@ -114,15 +110,11 @@ static int stmpe_read_temp(struct stmpe_adc *info,
 	stmpe_reg_write(info->stmpe, STMPE_REG_TEMP_CTRL,
 			STMPE_START_ONE_TEMP_CONV);
 
-	ret = wait_for_completion_interruptible_timeout
-		(&info->completion, STMPE_ADC_TIMEOUT);
+	ret = wait_for_completion_timeout(&info->completion, STMPE_ADC_TIMEOUT);
 
 	if (ret <= 0) {
 		mutex_unlock(&info->lock);
-		if (ret == 0)
-			return -ETIMEDOUT;
-		else
-			return ret;
+		return -ETIMEDOUT;
 	}
 
 	/*