drm/xe: Force user context allocations in user VRAM

drm/xe: Force user context allocations in user VRAM

In general, kernel structures should be allocated in the kernel-dedicated
VRAM region. However, userspace context data - while used by the kernel -
does not need to reside there.
Let's force the allocation of such data in the general-purpose VRAM region
accessible to userspace.

Signed-off-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://lore.kernel.org/r/20251003162619.1984236-4-piotr.piorkowski@intel.com