arm64: dts: r8a7796: salvator-x: Enable NFS root

Cfr. commit b2407c56 ("arm64: dts: r8a7795: enable nfs root on
Salvator-X board").
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a7796-salvator-x.dts

@@ -23,7 +23,7 @@ aliases {
 	};
 
 	chosen {
-		bootargs = "ignore_loglevel";
+		bootargs = "ignore_loglevel rw root=/dev/nfs ip=dhcp";
 		stdout-path = "serial0:115200n8";
 	};