ath79: specify "firmware" partition format for TP-LINK Archer C7 v2

With this change it doesn't require trying parsers one by one.

Signed-off-by: Rafał Miłecki <[email protected]>

target/linux/ath79/dts/qca9558_tplink_archer-c7-v2.dts

@@ -37,10 +37,11 @@
 
 	firmware@20000 {
 		reg = <0x020000 0xfd0000>;
+		compatible = "tplink,firmware";
 	};
 
 	art: art@ff0000 {
 		reg = <0xff0000 0x010000>;
 		read-only;
 	};
-};
+};