This patch adds a helper function that can be used to interpret most
"ranges" properties in the device tree.

It reads the n'th range out of a "ranges" array and returns the node's
virtual address of the range, the physical address that range starts at
and the size of the range.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Acked-by: NScott Wood <scottwood@freescale.com>
Reviewed-by: NYork Sun <yorksun@freescale.com>