ramips: fix firmware compatible string for dir860l-b1

In commit d70ec3008d, a firmware compatible
string of "denx,uimage" was added for the Dlink DIR-860L-B1. Unfortunately,
this was the wrong string. It needs "seama" instead.

Signed-off-by: Russell Senior <russell@personaltelco.net>

target/linux/ramips/dts/DIR-860L-B1.dts

@@ -112,7 +112,7 @@
 			};
 
 			partition@50000 {
-				compatible = "denx,uimage";
+				compatible = "seama";
 				label = "firmware";
 				reg = <0x50000 0xfb0000>;
 			};