ARM: shmobile: bockw: Move SPI FLASH partition to subnode

As of commits 5cfdedb7b9a0fe38 ("mtd: ofpart: move ofpart partitions to a
dedicated dt node") and fe2585e9c29a650a ("doc: dt: mtd: support partitions
in a special 'partitions' subnode"), having partitions as direct subnodes
of an mtd device is discouraged. Hence move the SPI FLASH partition to a
"partitions" subnode.

Based on similar work for the koelsch board by Geert Uytterhoeven.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7778-bockw.dts

@@ -188,16 +188,19 @@
 	status = "okay";
 
 	flash: flash@0 {
-		#address-cells = <1>;
-		#size-cells = <1>;
 		compatible = "spansion,s25fl008k", "jedec,spi-nor";
 		reg = <0>;
 		spi-max-frequency = <104000000>;
 		m25p,fast-read;
 
-		partition@0 {
-			label = "data(spi)";
-			reg = <0x00000000 0x00100000>;
+		partitions {
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			partition@0 {
+				label = "data(spi)";
+				reg = <0x00000000 0x00100000>;
+			};
 		};
 	};
 };