Legacy images replacement with multi-arch ones on AArch64

Replace those legacy docker images prefixed by 'aarch64/' and 'arm64v8/'
with official multi-arch ones.

Signed-off-by: Dennis Chen <dennis.chen@arm.com>

Dockerfile.aarch64

@@ -15,7 +15,7 @@
 # the case. Therefore, you don't have to disable it anymore.
 #
 
-FROM arm64v8/debian:stretch
+FROM debian:stretch
 
 # allow replacing httpredir or deb mirror
 ARG APT_MIRROR=deb.debian.org
@@ -142,10 +142,10 @@ RUN ln -sv $PWD/contrib/completion/bash/docker /etc/bash_completion.d/docker
 # Get useful and necessary Hub images so we can "docker load" locally instead of pulling
 COPY contrib/download-frozen-image-v2.sh /go/src/github.com/docker/docker/contrib/
 RUN ./contrib/download-frozen-image-v2.sh /docker-frozen-images \
-	aarch64/buildpack-deps:jessie@sha256:107f4a96837ed89c493fc205cd28508ed0b6b680b4bf3e514e9f0fa0f6667b77 \
-	aarch64/busybox:latest@sha256:5a06b8b2fdf22dd1f4085c6c3efd23ee99af01b2d668d286bc4be6d8baa10efb \
-	aarch64/debian:jessie@sha256:e6f90b568631705bd5cb27490977378ba762792b38d47c91c4da7a539f63079a \
-	aarch64/hello-world:latest@sha256:bd1722550b97668b23ede297abf824d4855f4d9f600dab7b4db1a963dae7ec9e
+	buildpack-deps:jessie@sha256:dd86dced7c9cd2a724e779730f0a53f93b7ef42228d4344b25ce9a42a1486251 \
+	busybox:latest@sha256:bbc3a03235220b170ba48a157dd097dd1379299370e1ed99ce976df0355d24f0 \
+	debian:jessie@sha256:287a20c5f73087ab406e6b364833e3fb7b3ae63ca0eb3486555dc27ed32c6e60 \
+	hello-world:latest@sha256:be0cd392e45be79ffeffa6b05338b98ebb16c87b255f48e297ec7f98e123905c
 # See also ensureFrozenImagesLinux() in "integration-cli/fixtures_linux_daemon_test.go" (which needs to be updated when adding images to this list)
 
 # Install tomlv, vndr, runc, containerd, tini, docker-proxy