fix missing classes argument to ResNet

Author: ovcharenkoo

MxNet/Classification/RN50v1.5/models.py

@@ -467,7 +467,7 @@ def create_resnet(builder, version, num_layers=50, resnext=False, classes=1000):
     block_class, layers, channels = resnet_spec[num_layers]
     assert not resnext or num_layers >= 50, \
         "Cannot create resnext with less then 50 layers"
-    net = ResNet(builder, block_class, layers, channels, version=version,
+    net = ResNet(builder, block_class, layers, channels, classes, version=version,
                  resnext_groups=args.num_groups if resnext else None)
     return net