Add support for the Raspberry Pi 2. As the chip is based on the bcm2835 in

Add support for the Raspberry Pi 2. As the chip is based on the bcm2835 in
the Raspberry Pi B we support most of the devices are already supported,
however the base address has changed.

A few items are not working, or missing. The main ones are:
 * DMA doesn't work in the sdhci driver.
 * Enabling vchiq halts the boot, may be interrupt related.
 * There is no U-Boot port yet so the DTB is embedded in the kernel.

The last point will make it difficult to boot FreeBSD, however there is
support for the Raspberry Pi 2 in the U-Boot git repo. As I have not tested
this it is left as an open task to create a port to build.

X-MFC:		When the above issues are fixed
Sponsored by:	ABT Systems Ltd