iio: accel: st_accel: Move platform data from header to C file

Platform data is solely used by one file. Don't share it with others.

While at it, drop unneeded anymore __maybe_unused and fix kernel doc
to avoid warning:

  st_accel_core.c:1079: error: Cannot parse struct or union!

by converting to a simple comment. It is described at the declaration.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210414195454.84183-1-andriy.shevchenko@linux.intel.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/accel/st_accel.h

@@ -62,14 +62,6 @@ enum st_accel_type {
 #define LIS2DE12_ACCEL_DEV_NAME		"lis2de12"
 #define LIS2HH12_ACCEL_DEV_NAME		"lis2hh12"
 
-/**
-* struct st_sensors_platform_data - default accel platform data
-* @drdy_int_pin: default accel DRDY is available on INT1 pin.
-*/
-static __maybe_unused const struct st_sensors_platform_data default_accel_pdata = {
-	.drdy_int_pin = 1,
-};
-
 const struct st_sensor_settings *st_accel_get_settings(const char *name);
 int st_accel_common_probe(struct iio_dev *indio_dev);
 void st_accel_common_remove(struct iio_dev *indio_dev);

drivers/iio/accel/st_accel_core.c

@@ -983,6 +983,11 @@ static const struct st_sensor_settings st_accel_sensors_settings[] = {
 
 };
 
+/* Default accel DRDY is available on INT1 pin */
+static const struct st_sensors_platform_data default_accel_pdata = {
+	.drdy_int_pin = 1,
+};
+
 static int st_accel_read_raw(struct iio_dev *indio_dev,
 			struct iio_chan_spec const *ch, int *val,
 							int *val2, long mask)