Adding improved MobileNetV2 weights (#5560)

* Adding improved MobileNetV2 weights

* Fix eval sizes.

* Update accuracy with batch-size 1 run

torchvision/prototype/models/mobilenetv2.py

@@ -13,11 +13,7 @@ from ._utils import handle_legacy_interface, _ovewrite_named_param
 __all__ = ["MobileNetV2", "MobileNet_V2_Weights", "mobilenet_v2"]
 
 
-class MobileNet_V2_Weights(WeightsEnum):
-    IMAGENET1K_V1 = Weights(
-        url="https://download.pytorch.org/models/mobilenet_v2-b0353104.pth",
-        transforms=partial(ImageNetEval, crop_size=224),
-        meta={
+_COMMON_META = {
     "task": "image_classification",
     "architecture": "MobileNetV2",
     "publication_year": 2018,
@@ -26,12 +22,31 @@ class MobileNet_V2_Weights(WeightsEnum):
     "min_size": (1, 1),
     "categories": _IMAGENET_CATEGORIES,
     "interpolation": InterpolationMode.BILINEAR,
+}
+
+
+class MobileNet_V2_Weights(WeightsEnum):
+    IMAGENET1K_V1 = Weights(
+        url="https://download.pytorch.org/models/mobilenet_v2-b0353104.pth",
+        transforms=partial(ImageNetEval, crop_size=224),
+        meta={
+            **_COMMON_META,
             "recipe": "https://github.com/pytorch/vision/tree/main/references/classification#mobilenetv2",
             "acc@1": 71.878,
             "acc@5": 90.286,
         },
     )
-    DEFAULT = IMAGENET1K_V1
+    IMAGENET1K_V2 = Weights(
+        url="https://download.pytorch.org/models/mobilenet_v2-7ebf99e0.pth",
+        transforms=partial(ImageNetEval, crop_size=224, resize_size=232),
+        meta={
+            **_COMMON_META,
+            "recipe": "https://github.com/pytorch/vision/issues/3995#new-recipe-with-reg-tuning",
+            "acc@1": 72.154,
+            "acc@5": 90.822,
+        },
+    )
+    DEFAULT = IMAGENET1K_V2
 
 
 @handle_legacy_interface(weights=("pretrained", MobileNet_V2_Weights.IMAGENET1K_V1))