COMPMID-2451: Use kernel lws_hint() on enqueue

Avoid querying device's default lws on kernel enqueue as this is already
cached in the kernel during configuration.

Change-Id: Ia26ecb712caeb8f042356815e0cfd23522764d27
Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Reviewed-on: https://review.mlplatform.org/c/1803
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/core/CL/kernels/CLMeanStdDevKernel.cpp b/src/core/CL/kernels/CLMeanStdDevKernel.cpp
index 0cde9c5..7bfd6d6 100644
--- a/src/core/CL/kernels/CLMeanStdDevKernel.cpp
+++ b/src/core/CL/kernels/CLMeanStdDevKernel.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2018 ARM Limited.
+ * Copyright (c) 2016-2019 ARM Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -132,7 +132,7 @@
         // Set slice step equal to height to force gws[1] to 1,
         // as each thread calculates the sum across all rows and columns equal to the number of elements processed by each work-item
         slice.set_dimension_step(Window::DimY, _input->info()->dimension(1));
-        enqueue(queue, *this, slice);
+        enqueue(queue, *this, slice, lws_hint());
     }
     while(window.slide_window_slice_2D(slice));