COMPMID-3313: Failed to compile master using gcc 8.1.1

Change-Id: Ied8adf220d6979b780d4bbe9c72d883cae362282
Signed-off-by: Michalis Spyrou <michalis.spyrou@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/2974
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/core/NEON/kernels/NERangeKernel.cpp b/src/core/NEON/kernels/NERangeKernel.cpp
index 2810722..fedb923 100644
--- a/src/core/NEON/kernels/NERangeKernel.cpp
+++ b/src/core/NEON/kernels/NERangeKernel.cpp
@@ -62,7 +62,7 @@
         const auto out_ptr = reinterpret_cast<T *>(output_it.ptr());
         for(; x <= (window_end_x - window_step_x); x += window_step_x)
         {
-            for(unsigned int count = 0; count < window_step_x; ++count)
+            for(int count = 0; count < window_step_x; ++count)
             {
                 id_vec = wrapper::vsetlane(static_cast<T>(x + count), id_vec, count);
             }