ramips: add support for Asus RT-N12+ B1 and RT-N300 B1

Asus RT-N12+ B1 and Asus RT-N300 B1 are the same device
with a different name.

The OEM firmwares have the same MD5 with Asus RT-N11P B1.

Same instructions for Asus RT-N11P B1 see:
commit c3dc52e39ac8 ("ramips: add support for Asus RT-N10P V3 / RT-N11P B1 / RT-N12 VP B1")

Signed-off-by: Semih Baskan <[email protected]>
(Added id from the PR review to commit message)
Signed-off-by: Christian Lamparter <[email protected]>

target/linux/ramips/image/mt76x8.mk

@@ -73,6 +73,12 @@ define Device/asus_rt-n11p-b1
   DEVICE_VENDOR := Asus
   DEVICE_MODEL := RT-N11P
   DEVICE_VARIANT := B1
+  DEVICE_ALT0_VENDOR := ASUS
+  DEVICE_ALT0_MODEL := RT-N12+
+  DEVICE_ALT0_VARIANT := B1
+  DEVICE_ALT1_VENDOR := ASUS
+  DEVICE_ALT1_MODEL := RT-N300
+  DEVICE_ALT1_VARIANT := B1
 endef
 TARGET_DEVICES += asus_rt-n11p-b1