ath79: add firmware partition compatible for OCEDO

This commit adds firmware partition compatible for the
OCEDO Raccoon and OCEDO Koala.

Since a22311e this allows to select the correct mtdsplit
parser instead of trying all available ones one by one.

Signed-off-by: David Bauer <mail@david-bauer.net>

target/linux/ath79/dts/ar9344_ocedo_raccoon.dts

@@ -105,6 +105,7 @@
 			};
 
 			partition@50000 {
+				compatible = "denx,uimage";
 				label = "firmware";
 				reg = <0x050000 0x740000>;
 			};

target/linux/ath79/dts/qca9558_ocedo_koala.dts

@@ -101,6 +101,7 @@
 			};
 
 			partition@50000 {
+				compatible = "denx,uimage";
 				label = "firmware";
 				reg = <0x050000 0x740000>;
 			};