iosys-map: refactor to reduce struct size

[Dave Airlie <airlied@gmail.com>]

Hey iosys_map users :)

I fell down a bit of a refactor hole today, it was just random and
sometimes you just have to let these things run their course.

I noticed iosys_map has a 7-byte hole in a 16-byte structure, and
it gets embedded into a bunch of other structs and it offended my
sensibilities.

This series makes iosys_map be 8-bytes, using the bottom bit of
the void * to store the is_iomem.

Patch 1: adds new accessors to start hiding internals
Patches 2-7: refactor all users in-tree to use new internals
(hopefully got them all)
Patch8: moves the internals around to catch anything not in-tree.
Patch9: reimplements iosys_map as 8-bytes by hiding the is_iomem
inside the pointer.

Dave.