Remove legacy armhf things in aarch64 Dockerfile

It's leftover from #20342 . We used to need this so we
can use armv6 binaries as bootstrap to build golang.
Now it's not needed.

Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>

Dockerfile.aarch64

@@ -52,11 +52,6 @@ RUN apt-get update && apt-get install -y \
 	iputils-ping \
 	--no-install-recommends
 
-# Install armhf loader to use armv6 binaries on armv8
-RUN dpkg --add-architecture armhf \
-	&& apt-get update \
-	&& apt-get install -y libc6:armhf
-
 # Get lvm2 source for compiling statically
 ENV LVM2_VERSION 2.02.103
 RUN mkdir -p /usr/local/lvm2 \