common: nameif: Handle nested dsa ports

In setups like this...

    CPU
    eth0
     |
.----0----.
| dst0sw0 |
'-1-2-3-4-'
        |
   .----0----.
   | dst1sw0 |
   '-1-2-3-4-'

...both eth0 and dst0sw0p4 are DSA ports. But the latter is _also_ a
physical port as far as devlink is concerned. As a result, it would
first be marked as "internal" and is then instantly reclassified as a
"port".

Catch this condition and stick with the initial "internal"
classification.

Author: wkz

board/common/rootfs/usr/libexec/infix/init.d/20-nameif

@@ -34,6 +34,12 @@ ports=$(devlink -j port | jq -r '.port[]
 				 | select(.flavour == "physical")
 				 | .netdev')
 for iface in $ports; do
+	# On systems with multiple switch trees, a port may be _both_
+	# a physical port, registered with devlink, _and_ a DSA
+	# port. In those cases, hold on to our initial "internal"
+	# classification.
+	[ $(ip -j link show dev "$iface" | jq -r '.[0].group') = internal ] && continue
+
 	ip link set "$iface" group port
 done