iio: hid: fix the retval in gyro_3d_capture_sample

Return value should be zero for success. This was forgotten for timestamp
feature. Verified on RealSense cameras.

Fixes: 4648cbd8fb92 ("iio: hid-sensor-gyro-3d: Add timestamp channel")
Signed-off-by: Dmitry Perchanov <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Cc: <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/gyro/hid-sensor-gyro-3d.c

···
 		gyro_state->timestamp =
 			hid_sensor_convert_timestamp(&gyro_state->common_attributes,
 						     *(s64 *)raw_data);
+		ret = 0;
 	break;
 	default:
 		break;