iio: hid-sensor-attributes: Fix gravity sensor scale value not right issue

Scale value include two parts: unit conversion and exponent conversion.
Add gravity unit convert table to fix gravity sensor scale value not
right issue.

Signed-off-by: Song Hongyan <hongyan.song@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/common/hid-sensors/hid-sensor-attributes.c

@@ -38,6 +38,12 @@ static struct {
 	{HID_USAGE_SENSOR_ACCEL_3D,
 		HID_USAGE_SENSOR_UNITS_G, 9, 806650000},
 
+	{HID_USAGE_SENSOR_GRAVITY_VECTOR, 0, 9, 806650000},
+	{HID_USAGE_SENSOR_GRAVITY_VECTOR,
+		HID_USAGE_SENSOR_UNITS_METERS_PER_SEC_SQRD, 1, 0},
+	{HID_USAGE_SENSOR_GRAVITY_VECTOR,
+		HID_USAGE_SENSOR_UNITS_G, 9, 806650000},
+
 	{HID_USAGE_SENSOR_GYRO_3D, 0, 0, 17453293},
 	{HID_USAGE_SENSOR_GYRO_3D,
 		HID_USAGE_SENSOR_UNITS_RADIANS_PER_SECOND, 1, 0},