drm/xe: Disable 32bits build

Add a dependency on CONFIG_64BIT since currently the xe driver doesn't
build on 32bits. It may be enabled again after all the issues are fixed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231221222809.4123220-2-lucas.demarchi@intel.com