Make the u-boot environment partition for the NETGEAR
GS108T v3 and GS110TPP writable (they share a DTS), so
the values can be manipulated from userspace.
See https://forum.openwrt.org/t/57875/1567 for a real
world example.
Signed-off-by: Stijn Segers <foss@volatilesystems.org>
(cherry picked from commit 9c381d3386)