imx7s-warp-u-boot: Fix aliases and chosen nodes indentation

The aliases and chosen nodes are currently indented using spaces.

Fix them to use the standard tab indentation.

Signed-off-by: Fabio Estevam <festevam@denx.de>

arch/arm/dts/imx7s-warp-u-boot.dtsi

@@ -1,12 +1,12 @@
 / {
-    aliases {
-        mmc0 = &usdhc3;
-        usb0 = &usbotg1;
-    };
+	aliases {
+		mmc0 = &usdhc3;
+		usb0 = &usbotg1;
+	};
 
-    chosen {
-        stdout-path = &uart1;
-    };
+	chosen {
+		stdout-path = &uart1;
+	};
 };
 
 &aips3 {