drm/i915: Distinction of memory regions

drm/i915: Distinction of memory regions

In preparation for Xe HP multi-tile architecture with multiple memory
regions, we need to be able differentiate multiple instances of device
local-memory.

Note that the region name is just to give it a human friendly
identifier, instead of using class/instance which also uniquely
identifies the region. So far the region name is only for our own
internal debugging in the kernel(like in the selftests), or debugfs
which prints the list of regions, including the regions name.

v2: add commentary for our current region name use

Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
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/20210203171231.551338-1-matthew.auld@intel.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>