rename config.hardware.dts.includes -> includePaths

(1) it's a better name
(2) I want to use `includes` to specify dtsi files

devices/gl-ar750/default.nix

@@ -116,7 +116,7 @@
         rootDevice = "/dev/mtdblock5";
         dts = {
           src = "${openwrt.src}/target/linux/ath79/dts/qca9531_glinet_gl-ar750.dts";
-          includes =  [
+          includePaths =  [
             "${openwrt.src}/target/linux/ath79/dts"
           ];
         };