Add gradient clip back in cfgs (#2608)

* Add gradient clip back in cfgs

* Reformat cfg

Co-authored-by: zww <zhangwenwei@sensetime.com>

configs/foveabox/fovea_align_r50_fpn_gn-head_4x4_2x_coco.py

@@ -6,3 +6,5 @@ model = dict(
 # learning policy
 lr_config = dict(step=[16, 22])
 total_epochs = 24
+optimizer_config = dict(
+    _delete_=True, grad_clip=dict(max_norm=35, norm_type=2))

configs/free_anchor/retinanet_free_anchor_r50_fpn_1x_coco.py

@@ -18,3 +18,5 @@ model = dict(
             target_means=[.0, .0, .0, .0],
             target_stds=[0.1, 0.1, 0.2, 0.2]),
         loss_bbox=dict(type='SmoothL1Loss', beta=0.11, loss_weight=0.75)))
+optimizer_config = dict(
+    _delete_=True, grad_clip=dict(max_norm=35, norm_type=2))

configs/ghm/retinanet_ghm_r50_fpn_1x_coco.py

@@ -15,3 +15,5 @@ model = dict(
             bins=10,
             momentum=0.7,
             loss_weight=10.0)))
+optimizer_config = dict(
+    _delete_=True, grad_clip=dict(max_norm=35, norm_type=2))