NormalizationLayer changes to enable fp16 in armv8a multi_isa builds

    * Moved the template arm_compute::normalize_float to impl.h because
      we need to instantiate it from both NENormalizationLayerKernel.cpp
      and src/cpu/kernels/norm_layer/generic/neon/fp16.cpp

    * Changes in filelist.json: added a new fp16.cpp file for the float16_t kernels

    * Replaced the guard __ARM_FEATURE_FP16_VECTOR_ARITHMETIC in
      NENormalizationLayerKernel by ARM_COMPUTE_ENABLE_FP16 so that
      the fp16 kernels can be compiled in for multi_isa builds

    * Moved fp32 kernels to the corresponding file
      src/cpu/kernels/norm_layer/generic/neon/fp32.cpp

    * Partially resolves MLCE-1102

Change-Id: I3f2eb2ed0b6c7f68092b17872b85082fbb5f39e2
Signed-off-by: Pablo Marquez Tello <pablo.tello@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/10739
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Viet-Hoa Do <viet-hoa.do@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Benchmark: Arm Jenkins <bsgcomp@arm.com>
diff --git a/filelist.json b/filelist.json
index d8c1692..ca8b18c 100644
--- a/filelist.json
+++ b/filelist.json
@@ -1913,7 +1913,11 @@
           "common": [
             "src/core/NEON/kernels/NENormalizationLayerKernel.cpp",
             "src/runtime/NEON/functions/NENormalizationLayer.cpp"
-          ]
+          ],
+        "neon":{
+          "fp16":["src/cpu/kernels/norm_layer/generic/neon/fp16.cpp"],
+          "fp32":["src/cpu/kernels/norm_layer/generic/neon/fp32.cpp"]
+        }
         }
       },
       "Pad": {