realtek: dsa: rename tagged_ports to member_ports

realtek: dsa: rename tagged_ports to member_ports

The current variables tagged_ports and untagged_ports suggest that
these are distinct and describe only the ports in each of these
configuration types.

That is wrong. The hardware is configured via member ports and
untagged ports. The first one being a superset of the second.
Rename the variables to reflect that.

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/19684
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>