meta-google: google-usb-network: Fix cleanup routine

The sysfs directories are not a real filesystem and do not behave
correctly if you use `rm -r`. You need to directly remove the relevant
files and directories individually.

Currently the script cannot successfully cleanup the interface.

Change-Id: Ic7eb104fa6491347d24681ac45b4c0433ea07b23
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/meta-google/recipes-google/networking/google-usb-network/usb_network.sh b/meta-google/recipes-google/networking/google-usb-network/usb_network.sh
index a135465..4ab4634 100755
--- a/meta-google/recipes-google/networking/google-usb-network/usb_network.sh
+++ b/meta-google/recipes-google/networking/google-usb-network/usb_network.sh
@@ -96,11 +96,11 @@
 gadget_stop() {
     local gadget_dir="${CONFIGFS_HOME}/usb_gadget/${GADGET_DIR_NAME}"
     rm -f ${gadget_dir}/configs/c.1/${DEV_TYPE}.${IFACE_NAME}
-    rm -rf ${gadget_dir}/configs/c.1/strings/0x409
-    rm -rf ${gadget_dir}/configs/c.1
-    rm -rf ${gadget_dir}/strings/0x409
-    rm -rf ${gadget_dir}/functions/${DEV_TYPE}.${IFACE_NAME}
-    rm -rf ${gadget_dir}
+    rmdir ${gadget_dir}/functions/${DEV_TYPE}.${IFACE_NAME} \
+      ${gadget_dir}/configs/c.1/strings/0x409 \
+      ${gadget_dir}/configs/c.1 \
+      ${gadget_dir}/strings/0x409 \
+      ${gadget_dir} || true
 
     rm -f /run/systemd/network/+-bmc-"${IFACE_NAME}".network
     networkctl reload