drm/xe/bo: add GPU memory trace points

drm/xe/bo: add GPU memory trace points

Add TRACE_GPU_MEM tracepoints for tracking global GPU memory usage.

These are required by VSR on Android 12+ for reporting GPU driver memory
allocations.

v5:
 - Drop process_mem tracking
 - Set the gpu_id field to dev->primary->index (Lucas, Tvrtko)
 - Formatting cleanup under 80 columns

v3:
 - Use now configurable CONFIG_TRACE_GPU_MEM instead of adding a
   per-driver Kconfig (Lucas)

v2:
 - Use u64 as preferred by checkpatch (Tvrtko)
 - Fix errors in comments/Kconfig description (Tvrtko)
 - drop redundant "CONFIG" in Kconfig

Signed-off-by: Juston Li <justonli@chromium.org>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250709192313.479336-2-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>