ath79-generic: (re)add support for GL-AR750 (#2454)

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

docs/user/supported_devices.rst

@@ -33,6 +33,7 @@ ath79-generic
 
   - GL-AR150
   - GL-AR300M-Lite
+  - GL-AR750
 
 * Joy-IT
 

targets/ath79-generic

@@ -97,6 +97,11 @@ device('gl.inet-gl-ar300m-lite', 'glinet_gl-ar300m-lite', {
 	factory = false,
 })
 
+device('gl.inet-gl-ar750', 'glinet_gl-ar750', {
+	factory = false,
+	packages = ATH10K_PACKAGES_QCA9887,
+})
+
 -- JOY-IT
 
 device('joy-it-jt-or750i', 'joyit_jt-or750i', {