realtek: dsa: Drop secondary LAG configuration handler

realtek: dsa: Drop secondary LAG configuration handler

The DSA code is responsible to inform the driver about link aggregation
changes. Having a second one which behaves slightly different makes the
whole process fragile and creates hard to debug problems.

It also complicates the code because the secondary event handler can also
not rely on shared DSA state to handle things like LAG ID.

Signed-off-by: Sven Eckelmann <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20707
Signed-off-by: Hauke Mehrtens <[email protected]>