ARM: shmobile: koelsch: Rename SCIF[01] serial ports to ttySC[01]

There's no reason to name the only two available serial ports on the
board ttySC6 and ttySC7 (apart from confusing userspace, which we should
try to avoid).
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7791-koelsch.dts

@@ -48,8 +48,8 @@ / {
 	compatible = "renesas,koelsch", "renesas,r8a7791";
 
 	aliases {
-		serial6 = &scif0;
-		serial7 = &scif1;
+		serial0 = &scif0;
+		serial1 = &scif1;
 	};
 
 	chosen {