Fix Nightly failing validation tests in NEON Reverse

Resolves COMPMID-6574

Signed-off-by: Adnan AlSinan <adnan.alsinan@arm.com>
Change-Id: I6b23e2a2f7b2839f038dad538dfc5ebda62891a6
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/10412
Benchmark: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Anitha Raj <Anitha.Raj@arm.com>
diff --git a/tests/validation/fixtures/ReverseFixture.h b/tests/validation/fixtures/ReverseFixture.h
index 8ff8cf9..7518a09 100644
--- a/tests/validation/fixtures/ReverseFixture.h
+++ b/tests/validation/fixtures/ReverseFixture.h
@@ -134,7 +134,7 @@
         {
             auto axis_data = AccessorType(axis);
             auto axis_v    = generate_random_axis(use_negative_axis);
-            std::copy(axis_v.begin(), axis_v.begin() + axis_shape.x(), static_cast<int32_t *>(axis_data.data()));
+            std::copy(axis_v.begin(), axis_v.begin() + _num_dims, static_cast<int32_t *>(axis_data.data()));
         }
 
         // Compute function