arm: bcmbca: add bcm6855 SoC support under CONFIG_ARCH_BCMBCA

BCM6855 is a Broadcom ARM A7 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_BCM6855 chip config and
CONFIG_ARCH_BCMBCA platform config.

This initial support includes a bare-bone implementation and dts with
CPU subsystem, memory and ARM PL101 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/dts/Makefile b/arch/arm/dts/Makefile
index 546a460..68630a7 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -1193,6 +1193,8 @@
 	bcm96813.dtb
 dtb-$(CONFIG_BCM6846) += \
 	bcm96846.dtb
+dtb-$(CONFIG_BCM6855) += \
+	bcm96855.dtb
 dtb-$(CONFIG_BCM6856) += \
 	bcm96856.dtb \
 	bcm968360bg.dtb