tests: lib: devicetree: api: Format app.overlay

Fix dts formatting issues with dts-linter.

Signed-off-by: Pieter De Gendt <pieter.degendt@basalte.be>

Author: pdgendt

tests/lib/devicetree/api/app.overlay

@@ -38,9 +38,13 @@
 
 		test_pinctrl: pin-controller {
 			compatible = "vnd,pinctrl";
+
 			test_pincfg_a: pincfg-a {};
+
 			test_pincfg_b: pincfg-b {};
+
 			test_pincfg_c: pincfg-c {};
+
 			test_pincfg_d: pincfg-d {};
 		};
 
@@ -252,20 +256,24 @@
 			test_i2c_mux: i2c-mux@12 {
 				compatible = "vnd,i2c-mux";
 				reg = <0x12>;
+
 				i2c-mux-ctlr-1 {
 					compatible = "vnd,i2c-mux-controller";
 					#address-cells = <1>;
 					#size-cells = <0>;
+
 					test_muxed_i2c_dev_1: muxed-i2c-dev@10 {
 						compatible = "vnd,i2c-device";
 						status = "disabled";
 						reg = <0x10>;
 					};
 				};
+
 				i2c-mux-ctlr-2 {
 					compatible = "vnd,i2c-mux-controller";
 					#address-cells = <1>;
 					#size-cells = <0>;
+
 					test_muxed_i2c_dev_2: muxed-i2c-dev@10 {
 						compatible = "vnd,i2c-device";
 						status = "disabled";
@@ -655,10 +663,12 @@
 				val = <0>;
 				status = "okay";
 			};
+
 			test_child_b: child-b {
 				val = <1>;
 				status = "okay";
 			};
+
 			test_child_c: child-c {
 				val = <2>;
 				status = "disabled";
@@ -852,6 +862,7 @@
 			flash@20000000 {
 				compatible = "soc-nv-flash";
 				reg = <0x20000000 0x100>;
+
 				partitions {
 					compatible = "fixed-partitions";
 					#address-cells = <1>;