COMPMID-2855: CLReduceMean throws error for invalid configs

Change-Id: Icc198a6db7dc79230972e12f226fa6fa1d9de6cb
Signed-off-by: Pablo Tello <pablo.tello@arm.com>
Reviewed-on: https://review.mlplatform.org/c/2452
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/arm_compute/runtime/CL/functions/CLReduceMean.h b/arm_compute/runtime/CL/functions/CLReduceMean.h
index 35501f5..20105a5 100644
--- a/arm_compute/runtime/CL/functions/CLReduceMean.h
+++ b/arm_compute/runtime/CL/functions/CLReduceMean.h
@@ -71,7 +71,7 @@
     std::vector<CLReductionOperation> _reduction_kernels;
     std::vector<CLTensor>             _reduced_outs;
     CLReshapeLayer                    _reshape;
-    unsigned int                      _reduction_ops;
+    int                               _reduction_ops;
     bool                              _keep_dims;
 };
 } // namespace arm_compute