of/address: Merge all of the bus translation code

Microblaze and PowerPC share a large chunk of code for translating
OF device tree data into usable addresses.  Differences between the two
consist of cosmetic differences, and the addition of dma-ranges support
code to powerpc but not microblaze.  This patch moves the powerpc
version into common code and applies many of the cosmetic (non-functional)
changes from the microblaze version.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Michal Simek <monstr@monstr.eu>
CC: Wolfram Sang <w.sang@pengutronix.de>
CC: Stephen Rothwell <sfr@canb.auug.org.au>