The y-axis of occupancy label is inversed and not aligned with nuScenes-OpenOcc

[sephyli]

In LightwheelOcc, the x-axis indices [0, 199] correspond to [-40, 40] m on the occupancy label. However, for the y-axis, indices [0, 199] correspond to [40, -40] m, which is the reverse of the x-axis. We will update the label accordingly.
Thanks to @ZM-Zhou for identifying this issue.