Fix doxygen references to new kernels

Resolves COMPMID-4117

Change-Id: I9945a92402e34b9cfe0ba9ef2a961b168bf62721
Signed-off-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/4883
Reviewed-by: Pablo Marquez Tello <pablo.tello@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/runtime/cpu/operators/CpuFill.h b/src/runtime/cpu/operators/CpuFill.h
index 7a75f42..fac8e76 100644
--- a/src/runtime/cpu/operators/CpuFill.h
+++ b/src/runtime/cpu/operators/CpuFill.h
@@ -30,7 +30,7 @@
 {
 namespace cpu
 {
-/** Basic function to run @ref CpuFillKernel */
+/** Basic function to run @ref kernels::CpuFillKernel */
 class CpuFill : public ICpuOperator
 {
 public: