arm64: dts: Add Broadcom North Star 2 support

Add Broadcom NS2 device tree binding document. Also add initial device
tree dtsi for Broadcom North Star 2 (NS2) SoC and board support for NS2
SVK board

Signed-off-by: Jon Mason <jonmason@broadcom.com>
Signed-off-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
diff --git a/arch/arm64/boot/dts/Makefile b/arch/arm64/boot/dts/Makefile
index 0c57290..1560478 100644
--- a/arch/arm64/boot/dts/Makefile
+++ b/arch/arm64/boot/dts/Makefile
@@ -1,6 +1,7 @@
 dts-dirs += amd
 dts-dirs += apm
 dts-dirs += arm
+dts-dirs += broadcom
 dts-dirs += cavium
 dts-dirs += exynos
 dts-dirs += freescale