iio: accel: st_sensors: Support generic mounting matrix

The ST accelerators support a special type of quirky mounting matrix found
in ACPI systems, but not a generic mounting matrix such as from the device
tree.

Augment the ACPI hack to be a bit more generic and accept a mounting
matrix from device properties.

This makes it possible to fix orientation on the Ux500 HREF device.

Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Denis Ciocca <denis.ciocca@st.com>
Cc: Daniel Drake <drake@endlessm.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210518230722.522446-2-linus.walleij@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

include/linux/iio/common/st_sensors.h

@@ -13,6 +13,7 @@
 #include <linux/i2c.h>
 #include <linux/spi/spi.h>
 #include <linux/irqreturn.h>
+#include <linux/iio/iio.h>
 #include <linux/iio/trigger.h>
 #include <linux/bitops.h>
 #include <linux/regulator/consumer.h>
@@ -221,6 +222,7 @@ struct st_sensor_settings {
  * struct st_sensor_data - ST sensor device status
  * @dev: Pointer to instance of struct device (I2C or SPI).
  * @trig: The trigger in use by the core driver.
+ * @mount_matrix: The mounting matrix of the sensor.
  * @sensor_settings: Pointer to the specific sensor settings in use.
  * @current_fullscale: Maximum range of measure by the sensor.
  * @vdd: Pointer to sensor's Vdd power supply
@@ -240,7 +242,7 @@ struct st_sensor_settings {
 struct st_sensor_data {
 	struct device *dev;
 	struct iio_trigger *trig;
-	struct iio_mount_matrix *mount_matrix;
+	struct iio_mount_matrix mount_matrix;
 	struct st_sensor_settings *sensor_settings;
 	struct st_sensor_fullscale_avl *current_fullscale;
 	struct regulator *vdd;