iio: add modifers for pitch, yaw, roll

Add modifiers for reporting rotations as euler angles (i.e. yaw, pitch and
roll).
Signed-off-by: Andrea Merello <andrea.merello@iit.it>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220907132205.28021-5-andrea.merello@iit.itSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/industrialio-core.c

@@ -137,6 +137,9 @@ static const char * const iio_modifier_names[] = {
 	[IIO_MOD_LINEAR_X] = "linear_x",
 	[IIO_MOD_LINEAR_Y] = "linear_y",
 	[IIO_MOD_LINEAR_Z] = "linear_z",
+	[IIO_MOD_PITCH] = "pitch",
+	[IIO_MOD_YAW] = "yaw",
+	[IIO_MOD_ROLL] = "roll",
 };
 
 /* relies on pairs of these shared then separate */

include/uapi/linux/iio/types.h

@@ -98,6 +98,9 @@ enum iio_modifier {
 	IIO_MOD_LINEAR_X,
 	IIO_MOD_LINEAR_Y,
 	IIO_MOD_LINEAR_Z,
+	IIO_MOD_PITCH,
+	IIO_MOD_YAW,
+	IIO_MOD_ROLL,
 };
 
 enum iio_event_type {