ath79-generic: (re)add wzr-hp-g300nh-s (#2551)

Note: Buffalo has introduced hardware changes without bumping the
revision number. 19.07 did not support the rb-variant so there's no need
to implement a migration for the rb-variant.
Every g300nh supported by Gluon should either be the s-variant or
been flashed wrongly.

Gone due to
commit 45c84a117b ("ar71xx: drop target")

docs/user/supported_devices.rst

@@ -17,6 +17,7 @@ ath79-generic
 * Buffalo
 
   - WZR-HP-AG300H / WZR-600DHP
+  - WZR-HP-G300NH (rtl8366s)
 
 * devolo
 

targets/ath79-generic

@@ -41,6 +41,12 @@ device('avm-fritz-wlan-repeater-450e', 'avm_fritz450e', {
 device('buffalo-wzr-hp-ag300h', 'buffalo_wzr-hp-ag300h')
 device('buffalo-wzr-600dhp', 'buffalo_wzr-600dhp')
 
+device('buffalo-wzr-hp-g300nh-rtl8366s', 'buffalo_wzr-hp-g300nh-s', {
+	manifest_aliases = {
+		'buffalo-wzr-hp-g300nh', -- Upgrade from OpenWrt 19.07
+	},
+})
+
 -- devolo
 
 device('devolo-wifi-pro-1200e', 'devolo_dvl1200e', {