drm/xe: Add cpu_caching to properties line in VM snapshot capture

drm/xe: Add cpu_caching to properties line in VM snapshot capture

Add CPU caching to properties line in VM snapshot capture indicating
the BO caching properites. This is useful information for debug and
will help build a robust GPU hang replay tool.

The current format is:

[<vma address>]: <permissions>|<type>|mem_region=0x%x|pat_index=%d|cpu_caching=%d

Permissions has two options, either "read_only" or "read_write".

Type has three options, either "userptr", "null_sparse", or "bo".

Memory region is a bit mask of where the memory is located.

Pat index corresponds to the value setup upon VM bind.

CPU caching corresponds to the value of BO setup upon creation.

v2:
 - Save off cpu_caching value rather than looking at BO (Carlos)
v4:
 - Fix NULL ptr dereference (Carlos)

Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patch.msgid.link/20251126185952.546277-6-matthew.brost@intel.com