DirectConv and Im2Col changes to enable fp16 in armv8a multi_isa builds

* FP16 kernels must be instantiated in fp16.cpp.
* Partially resolves MLCE-1102

Change-Id: Iab9c29dbfd89358f2f663862ff5010c88aeccf8c
Signed-off-by: Pablo Marquez Tello <pablo.tello@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/10496
Reviewed-by: Anitha Raj <Anitha.Raj@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Benchmark: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/BUILD.bazel b/src/BUILD.bazel
index 48973df..a22632e 100644
--- a/src/BUILD.bazel
+++ b/src/BUILD.bazel
@@ -745,8 +745,11 @@
 	"cpu/kernels/depthwiseconv2d/generic/neon/qasymm8.cpp",
 	"cpu/kernels/depthwiseconv2d/generic/neon/qasymm8_signed.cpp",
 	"cpu/kernels/directconv2d/nchw/all.cpp",
+	"cpu/kernels/directconv2d/nchw/fp16.cpp",
+	"cpu/kernels/directconv2d/nhwc/neon/fp16.cpp",
 	"cpu/kernels/directconv2d/nhwc/neon/fp32.cpp",
 	"cpu/kernels/directconv2d/nhwc/neon/impl.cpp",
+	"cpu/kernels/directconv2d/nhwc/neon/qasymm8.cpp",
 	"cpu/kernels/elementwise_binary/generic/neon/fp16.cpp",
 	"cpu/kernels/elementwise_binary/generic/neon/fp32.cpp",
 	"cpu/kernels/elementwise_binary/generic/neon/integer.cpp",