fix: error of sample_points when num_point < far_idx_choice

In data_processor.py sample_points, when num_points < far_idx_choice, a negative value is passed into np.random.choice, which cause a ValueError.
In fact the variable `near_idxs_choice` return by the deleted line is never used.

pcdet/datasets/processor/data_processor.py

@@ -88,7 +88,6 @@ class DataProcessor(object):
             pts_near_flag = pts_depth < 40.0
             far_idxs_choice = np.where(pts_near_flag == 0)[0]
             near_idxs = np.where(pts_near_flag == 1)[0]
-            near_idxs_choice = np.random.choice(near_idxs, num_points - len(far_idxs_choice), replace=False)
             choice = []
             if num_points > len(far_idxs_choice):
                 near_idxs_choice = np.random.choice(near_idxs, num_points - len(far_idxs_choice), replace=False)