Add bsdmainutils tool to Dockerfile to enable integration test on arm64

Build image for integration test on arm64 will fail for lack of
hexdump. Add bsdmainutils tool to eliminate that failure and let
build image succussfully

Signed-off-by: Jianyong Wu <jianyong.wu@arm.com>

Dockerfile

@@ -38,6 +38,7 @@ RUN apt-get update && apt-get install -y \
     netcat \
     socat \
     --no-install-recommends \
+    bsdmainutils \
     && apt-get clean
 
 # install bats