ath79-nand: (re)add hiveap-121

Direct migration from 19.07 is currently not possible.

Gone due to
commit 45c84a11 ("ar71xx: drop target")

docs/user/supported_devices.rst

@@ -139,6 +139,10 @@ ath79-generic
 ath79-nand
 ----------
 
+* Aerohive
+
+  - HiveAP 121
+
 * GL.iNet
 
   - GL-AR300M

targets/ath79-nand

@@ -9,6 +9,11 @@ local ATH10K_PACKAGES_QCA9887 = {
 local ATH10K_PACKAGES_QCA9888 = {}
 
 
+-- Aerohive
+
+device('aerohive-hiveap-121', 'aerohive_hiveap-121')
+
+
 -- GL.iNet
 
 device('gl.inet-gl-ar300m-nor', 'glinet_gl-ar300m-nor', {