ARM: kirkwood: Basic support for DNS-320 and DNS-325

Add support for the DNS-320 and DNS-325. Describe as much as currently possible
in the devicetree files, create a board-dnskw.c for everything else.

Changes since last submission (V3) [Addressing comments by]:-

* One MACH_DLINK_KIRKWOOD_DT for all dtb files [Grant Likely, Jason Cooper]
* Drop brain-dead select "select CONFIG_MTD_OF_PARTS" [Grant Likely]
* Don't add NAND support then throw it away immediately after [Grant Likely]
* Describe purpose of MPP 41, 42 & 49

Changes since last submission (V2):-

* Use IEEE-compliant "okay", rather than "ok" [Scott Wood]

Signed-off-by: Jamie Lentin <jm@lentin.co.uk>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
diff --git a/arch/arm/boot/dts/kirkwood-dns325.dts b/arch/arm/boot/dts/kirkwood-dns325.dts
new file mode 100644
index 0000000..23241ab
--- /dev/null
+++ b/arch/arm/boot/dts/kirkwood-dns325.dts
@@ -0,0 +1,24 @@
+/dts-v1/;
+
+/include/ "kirkwood.dtsi"
+
+/ {
+	model = "D-Link DNS-325 NAS (Rev A1)";
+	compatible = "dlink,dns-325-a1", "dlink,dns-325", "dlink,dns-kirkwood", "mrvl,kirkwood-88f6281", "mrvl,kirkwood";
+
+	memory {
+		device_type = "memory";
+		reg = <0x00000000 0x10000000>;
+	};
+
+	chosen {
+		bootargs = "console=ttyS0,115200n8 earlyprintk";
+	};
+
+	ocp@f1000000 {
+		serial@12000 {
+			clock-frequency = <200000000>;
+			status = "okay";
+		};
+	};
+};