drm/i915: cleanup the region class/instance encoding

Get rid of the strange REGION_MAP encoding stuff and just use an
explicit class/instance pair for each region. This better matches our
future uAPI where all queryable regions are identified with a u16 class
and u16 instance.

v2: fix whitespace

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20210205102026.806699-1-matthew.auld@intel.com


Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>