arm: bcmbca: add bcm6856 SoC support under CONFIG_ARCH_BCMBCA

BCM6856 is a Broadcom B53 based PON Gateway SoC. It is part of the BCA
(Broadband Carrier Access origin) chipset family. Like other Broadband
SoC, this patch adds it under CONFIG_BCM6856 chip config and
CONFIG_ARCH_BCMBCA platform config.

This initial support includes a bare-bone implementation and dts with
CPU subsystem, memory and Broadcom uart. This SoC is supported in the
linux-next git repository so the dts and dtsi files are copied from
linux.

The u-boot image can be loaded from flash or network to the entry point
address in the memory and boot from there to the console.

Signed-off-by: William Zhang <william.zhang@broadcom.com>
Reviewed-by: Philippe Reynes <philippe.reynes@softathome.com>
diff --git a/arch/arm/mach-bcmbca/Makefile b/arch/arm/mach-bcmbca/Makefile
index e5df60e..20f8275 100644
--- a/arch/arm/mach-bcmbca/Makefile
+++ b/arch/arm/mach-bcmbca/Makefile
@@ -14,4 +14,5 @@
 obj-$(CONFIG_BCM6756) += bcm6756/
 obj-$(CONFIG_BCM6813) += bcm6813/
 obj-$(CONFIG_BCM6846) += bcm6846/
+obj-$(CONFIG_BCM6856) += bcm6856/
 obj-$(CONFIG_BCM6878) += bcm6878/