Fix duplicated argname: num_gpus === parts (keras-team#10228)

Signed-off-by: CUI Wei <[email protected]>

Author: ghostplant

keras/utils/multi_gpu_utils.py

@@ -184,7 +184,7 @@ def get_slice(data, i, parts):
         batch_size = shape[:1]
         input_shape = shape[1:]
         step = batch_size // parts
-        if i == num_gpus - 1:
+        if i == parts - 1:
             size = batch_size - step * i
         else:
             size = step