iio: adc: ti-adc161s626: add regulator support

Hello Matt Ranostay,

The patch 92f0afb5b2be: "iio: adc: ti-adc161s626: add regulator support" from Sep 18, 2016, leads to the following static checker warning:

	drivers/iio/adc/ti-adc161s626.c:237 ti_adc_probe()
	error: 'data->ref' dereferencing possible ERR_PTR()

drivers/iio/adc/ti-adc161s626.c
214
215 data->ref = devm_regulator_get(&spi->dev, "vdda");
216 if (!IS_ERR(data->ref)) {
217 ret = regulator_enable(data->ref);
218 if (ret < 0)
219 return ret;
220 }

This code assumes that devm_regulator_get() can fail and we continue with what we have, but none of the rest of the driver assumes that.

   221  
   222          ret = iio_triggered_buffer_setup(indio_dev, NULL,
   223                                           ti_adc_trigger_handler, NULL);
   224          if (ret)
   225                  goto error_regulator_disable;
   226  
   227          ret = iio_device_register(indio_dev);
   228          if (ret)
   229                  goto error_unreg_buffer;
   230  
   231          return 0;
   232  
   233  error_unreg_buffer:
   234          iio_triggered_buffer_cleanup(indio_dev);
   235  
   236  error_regulator_disable:
   237          regulator_disable(data->ref);

Every reference to "data->ref" needs to be updated to wrapped in "if (!IS_ERR(data->ref)) " otherwise it will oops.

238
239 return ret;
240 }

regards,
dan carpenter