CpuSubKernel changes to enable fp16 in armv8a multi_isa builds

    * FP16 kernels must be instantiated in fp16.cpp.

    * Partially resolves MLCE-1102

Change-Id: I497fe0ba6e84493a5072c3e80bbba7ecd5de8095
Signed-off-by: Pablo Marquez Tello <pablo.tello@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/10448
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 bb90fcf..aeb54c6 100644
--- a/filelist.json
+++ b/filelist.json
@@ -2249,13 +2249,17 @@
           "common": [
             "src/cpu/operators/CpuSub.cpp",
             "src/cpu/kernels/CpuSubKernel.cpp",
-            "src/runtime/NEON/functions/NEArithmeticSubtraction.cpp",
-            "src/cpu/kernels/sub/neon/qasymm8.cpp",
-            "src/cpu/kernels/sub/neon/qasymm8_signed.cpp",
-            "src/cpu/kernels/sub/neon/qsymm16.cpp"
-          ]
+            "src/runtime/NEON/functions/NEArithmeticSubtraction.cpp"
+          ],
+          "neon": {
+            "fp16":["src/cpu/kernels/sub/neon/fp16.cpp"],
+            "qasymm8": ["src/cpu/kernels/sub/neon/qasymm8.cpp"],
+            "qasymm8_signed": ["src/cpu/kernels/sub/neon/qasymm8_signed.cpp"],
+            "qsymm16": ["src/cpu/kernels/sub/neon/qsymm16.cpp"]
+          }
         }
       },
+
       "Tile": {
         "files": {
           "common": [