board: arm: Add support for Broadcom BCM7445

Add support for loading U-Boot on the Broadcom 7445 SoC.  This port
assumes Broadcom's BOLT bootloader is acting as the second stage
bootloader, and U-Boot is acting as the third stage bootloader, loaded
as an ELF program by BOLT.

Signed-off-by: Thomas Fitzsimmons <fitzsim@fitzsim.org>
Cc: Stefan Roese <sr@denx.de>
Cc: Tom Rini <trini@konsulko.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
diff --git a/dts/Kconfig b/dts/Kconfig
index 0cef225..a1a92f2 100644
--- a/dts/Kconfig
+++ b/dts/Kconfig
@@ -101,6 +101,13 @@
 	  This is only useful for Sandbox.  Use the -d flag to U-Boot to
 	  specify the file to read.
 
+config OF_PRIOR_STAGE
+	bool "Prior stage bootloader DTB for DT control"
+	help
+	  If this option is enabled, the device tree used for DT
+	  control will be read from a device tree binary, at a memory
+	  location passed to U-Boot by the prior stage bootloader.
+
 endchoice
 
 config DEFAULT_DEVICE_TREE