drm/xe/query: zero the region info

There are also some reserved fields in here which are not currently
cleared when handing back to userspace. Otherwise we might run into
issues if we later wish to use them.

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