uapi/drm/i915: Document memory residency and Flat-CCS capability of obj

uapi/drm/i915: Document memory residency and Flat-CCS capability of obj

Capture the impact of memory region preference list of the objects, on
their memory residency and Flat-CCS capability.

v2:
  Fix the Flat-CCS capability of an obj with {lmem, smem} preference
  list [Thomas]
v3:
  Reworded the doc [Matt]
v4:
  Fixed Typos and spelling mistakes [Tvrtko, Joonas]

Signed-off-by: Ramalingam C <[email protected]>
cc: Matthew Auld <[email protected]>
cc: Thomas Hellstrom <[email protected]>
cc: Daniel Vetter <[email protected]>
cc: Jon Bloomfield <[email protected]>
cc: Lionel Landwerlin <[email protected]>
cc: Kenneth Graunke <[email protected]>
cc: [email protected]
cc: Jordan Justen <[email protected]>
cc: Tony Ye <[email protected]>
Reviewed-by: Matthew Auld <[email protected]>
Acked-by: Jordan Justen <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]