Remove usage of valid window region CL - NHWC

Resolves: COMPMID-4153

Change-Id: Ib0d60c9acaac8aaf3946c62fc2d740b5ec6cee5c
Signed-off-by: Michalis Spyrou <michalis.spyrou@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/5301
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/core/CL/kernels/CLIm2ColKernel.cpp b/src/core/CL/kernels/CLIm2ColKernel.cpp
index 07309de..6710581 100644
--- a/src/core/CL/kernels/CLIm2ColKernel.cpp
+++ b/src/core/CL/kernels/CLIm2ColKernel.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2020 Arm Limited.
+ * Copyright (c) 2017-2021 Arm Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -147,7 +147,7 @@
             win = calculate_max_window(*input, Steps());
         }
     }
-    output->set_valid_region(ValidRegion(Coordinates(), output->tensor_shape()));
+
     // set the Z dimension's step same size as the whole dimension so that one can't split across the Z dimension
     win.set_dimension_step(Window::DimZ, win[Window::DimZ].end() - win[Window::DimZ].start());