iio: cros_ec: unify hw fifo attributes into the core file

The intent here is to minimize the use of iio_buffer_set_attrs(). Since we
are planning to add support for multiple IIO buffers per IIO device, the
issue has to do with:
1. Accessing 'indio_dev->buffer' directly (as is done with
   'iio_buffer_set_attrs(indio_dev->buffer, <attrs>)').
2. The way that the buffer attributes would get handled or expanded when
   there are more buffers per IIO device. Current a sysfs kobj_type expands
   into a 'device' object that expands into an 'iio_dev' object.
   We will need to change this, so that the sysfs attributes for IIO
   buffers expand into IIO buffers at some point.

Right now, the current IIO framework works fine for the
'1 IIO device == 1 IIO buffer' case (that is now).

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Link: https://lore.kernel.org/r/20200923130339.997902-1-alexandru.ardelean@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

include/linux/iio/common/cros_ec_sensors_core.h

@@ -96,7 +96,8 @@ struct platform_device;
 int cros_ec_sensors_core_init(struct platform_device *pdev,
 			      struct iio_dev *indio_dev, bool physical_device,
 			      cros_ec_sensors_capture_t trigger_capture,
-			      cros_ec_sensorhub_push_data_cb_t push_data);
+			      cros_ec_sensorhub_push_data_cb_t push_data,
+			      bool has_hw_fifo);
 
 irqreturn_t cros_ec_sensors_capture(int irq, void *p);
 int cros_ec_sensors_push_data(struct iio_dev *indio_dev,
@@ -125,6 +126,5 @@ extern const struct dev_pm_ops cros_ec_sensors_pm_ops;
 
 /* List of extended channel specification for all sensors. */
 extern const struct iio_chan_spec_ext_info cros_ec_sensors_ext_info[];
-extern const struct attribute *cros_ec_sensor_fifo_attributes[];
 
 #endif  /* __CROS_EC_SENSORS_CORE_H */