COMPMID-1451: Fix validation issue in CLReduceMean

Change-Id: Ie1bcdd9dca2dc3b26003790a19cc80bb953385b2
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/155373
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Tested-by: bsgcomp <bsgcomp@arm.com>
diff --git a/src/runtime/CL/functions/CLReduceMean.cpp b/src/runtime/CL/functions/CLReduceMean.cpp
index 02e341a..1016ff7 100644
--- a/src/runtime/CL/functions/CLReduceMean.cpp
+++ b/src/runtime/CL/functions/CLReduceMean.cpp
@@ -103,7 +103,7 @@
             ARM_COMPUTE_RETURN_ERROR_ON(output->dimension(reduction_axis[i]) != 1);
         }
 
-        ARM_COMPUTE_RETURN_ON_ERROR(CLReductionOperationKernel::validate(input, output, reduction_axis[i], ReductionOperation::MEAN_SUM, 0));
+        ARM_COMPUTE_RETURN_ON_ERROR(CLReductionOperation::validate(input, output, reduction_axis[i], ReductionOperation::MEAN_SUM));
     }
 
     return Status{};