For some reason the highmem configuration of RTL930x
devices was totally missed until now. Take over the
setup from the SDK. This will avoid boot stalls on
switches with more than 256 MB RAM when switching
over to kernel 6.18.
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/21327
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>