modified single gpu init

pytorch_lightning/models/trainer.py

@@ -320,7 +320,7 @@ class Trainer(TrainerIO):
 
     def single_gpu_train(self, model):
         torch.cuda.set_device(0)
-        model = model.cuda(0)
+        model.cuda(0)
 
         # CHOOSE OPTIMIZER
         # filter out the weights that were done on gpu so we can load on good old cpus