drm/xe: prefer xe_bo_create_pin_map()

With small-bar we likely want to annotate all the kernel users that
require CPU access with vram. If xe_bo_create_pin_map() is the central
place for that then we should have a central place to annotate.

This also simplifies the code and fixes what appears to be a double
xe_bo_put(hwe->hwsp) in the error handling.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>