ramips-mt76x8: add support for TP-Link Archer C20 v4 (#2500)

Co-authored-by: Ilja Gerhardt <ilja@cryptix.net>

Co-authored-by: Ilja Gerhardt <ilja@cryptix.net>

docs/user/supported_devices.rst

@@ -323,7 +323,7 @@ ramips-mt76x8
 
 * TP-Link
 
-  - Archer C20 (v5)
+  - Archer C20 (v4, v5)
   - Archer C50 (v3)
   - Archer C50 (v4)
   - RE200 (v2)

targets/ramips-mt76x8

@@ -32,6 +32,13 @@ device('ravpower-rp-wd009', 'ravpower_rp-wd009')
 
 -- TP-Link
 
+device('tp-link-archer-c20-v4', 'tplink_archer-c20-v4', {
+	factory = false,
+	extra_images = {
+		{'-squashfs-tftp-recovery', '-bootloader', '.bin'},
+	},
+})
+
 device('tp-link-archer-c20-v5', 'tplink_archer-c20-v5', {
 	factory = false,
 })