ARM: shmobile: marzen: tidyup DT node naming

According to ePAPR spec,
this patch tidies up DT node name.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7779-marzen-reference.dts

@@ -82,17 +82,17 @@ lbsc {
 		};
 	};
 
-	scif2_pins: scif2 {
+	scif2_pins: serial2 {
 		renesas,groups = "scif2_data_c";
 		renesas,function = "scif2";
 	};
 
-	scif4_pins: scif4 {
+	scif4_pins: serial4 {
 		renesas,groups = "scif4_data";
 		renesas,function = "scif4";
 	};
 
-	sdhi0_pins: sdhi0 {
+	sdhi0_pins: sd0 {
 		renesas,groups = "sdhi0_data4", "sdhi0_ctrl", "sdhi0_cd",
 				 "sdhi0_wp";
 		renesas,function = "sdhi0";