MLBEDSW-3774 Remove SplitSliceRead

Removed SplitSliceRead from subgraph during
graph optimisation.

Signed-off-by: Patrik Gustavsson <patrik.gustavsson@arm.com>
Change-Id: I9315d4c2a6767828dd2b4e66823d73b10ebee99c
diff --git a/ethosu/vela/high_level_command_stream.py b/ethosu/vela/high_level_command_stream.py
index c25c023..0ce8fac 100644
--- a/ethosu/vela/high_level_command_stream.py
+++ b/ethosu/vela/high_level_command_stream.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2020 Arm Limited or its affiliates. All rights reserved.
+# Copyright (C) 2020-2021 Arm Limited or its affiliates. All rights reserved.
 #
 # SPDX-License-Identifier: Apache-2.0
 #
@@ -41,7 +41,7 @@
         npu_block_type: NpuBlockType,
         concat_axis: int = 0,
         concat_offset: int = 0,
-        split_offset: int = None,
+        split_offset: Shape4D = None,
         k_height: int = 1,
         upscaling_factor: int = 1,
     ):