gluon-core: read NanoPi R2S primary MAC from LAN board data

The relevant entry for the primary MAC location was lost when rebasing
the patch on OpenWrt 21.02.

Fixes commit ded4b8a7 ("rockchip-armv8: add FriendlyARM NanoPi R2S")

Signed-off-by: David Bauer <mail@david-bauer.net>

package/gluon-core/luasrc/lib/gluon/upgrade/010-primary-mac

@@ -99,6 +99,9 @@ local primary_addrs = {
 		{'ramips', 'mt76x8', {
 			'xiaomi,mi-router-4a-100m',
 		}},
+		{'rockchip', 'armv8', {
+			'friendlyarm,nanopi-r2s',
+		}},
 		{'x86'},
 	}},
 	{interface('wan'), {