arm: bcmbca: add bcm4912 SoC support

BCM4912 is a Broadcom B53 based WLAN AP router SoC. It is part of the
BCA (Broadband Carrier Access origin) chipset family so it's added under
ARCH_BCMBCA platform. This initial support includes a bare-bone
implementation and dts with CPU subsystem, memory and ARM PL011 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: Florian Fainelli <f.fainelli@gmail.com>
diff --git a/arch/arm/mach-bcmbca/Makefile b/arch/arm/mach-bcmbca/Makefile
index e177b62..e9c9660 100644
--- a/arch/arm/mach-bcmbca/Makefile
+++ b/arch/arm/mach-bcmbca/Makefile
@@ -4,6 +4,7 @@
 #
 
 obj-$(CONFIG_BCM47622) += bcm47622/
+obj-$(CONFIG_BCM4912) += bcm4912/
 obj-$(CONFIG_BCM63138) += bcm63138/
 obj-$(CONFIG_BCM63146) += bcm63146/
 obj-$(CONFIG_BCM63148) += bcm63148/