[Build] Fix libyang build broken issue

files/build_templates/sonic_debian_extension.j2

@@ -266,6 +266,10 @@ sudo LANG=C DEBIAN_FRONTEND=noninteractive chroot $FILESYSTEM_ROOT apt-get -y -t
 sudo LANG=C DEBIAN_FRONTEND=noninteractive chroot $FILESYSTEM_ROOT apt-get -y install gir1.2-glib-2.0 libdbus-1-3 libgirepository-1.0-1
 sudo LANG=C DEBIAN_FRONTEND=noninteractive chroot $FILESYSTEM_ROOT apt-get -y -t $IMAGE_DISTRO-backports install libsystemd0
 
+if [[ $CONFIGURED_ARCH == armhf ]]; then
+    sudo https_proxy=$https_proxy LANG=C chroot $FILESYSTEM_ROOT pip3 install dbus-python==1.2.18
+fi
+
 # Install SONiC host services package
 SONIC_HOST_SERVICES_PY3_WHEEL_NAME=$(basename {{sonic_host_services_py3_wheel_path}})
 sudo cp {{sonic_host_services_py3_wheel_path}} $FILESYSTEM_ROOT/$SONIC_HOST_SERVICES_PY3_WHEEL_NAME

sonic-slave-buster/Dockerfile.j2

@@ -354,9 +354,6 @@ RUN apt-get update && apt-get install -y \
         libsystemd-dev \
         pkg-config
 
-# Upgrade cmake to support dbus-python build in armhf
-RUN apt-get install -t buster-backports -y cmake
-
 RUN apt-get -y build-dep openssh
 
 # Build fix for ARMHF buster libsairedis
@@ -380,6 +377,9 @@ RUN apt-get -y build-dep openssh
 
        # workaround because of https://bugs.launchpad.net/qemu/+bug/1805913, just disable aspell
        RUN cp /bin/true /usr/bin/aspell
+
+       # The cmake (>3.15) is required to install the latest version of dbus-python in armhf, but the cmake will conflict with libyang
+       RUN pip3 install dbus-python==1.2.18
 {%- endif %}
 
 ## Config dpkg