gluon-config-mode-geo-location: remove uci:set() nil check

simple-uci will now delete an option when nil is passed.

package/gluon-config-mode-geo-location/luasrc/lib/gluon/config-mode/wizard/0400-geo-location.lua

@@ -52,11 +52,7 @@ return function(form, uci)
 		o.datatype = "float"
 		o.optional = true
 		function o:write(data)
-			if data then
-				uci:set("gluon-node-info", location, "altitude", data)
-			else
-				uci:delete("gluon-node-info", location, "altitude")
-			end
+			uci:set("gluon-node-info", location, "altitude", data)
 		end
 	end