drm/xe/vm: Fix a misplaced #endif

Fix a (harmless) misplaced #endif leading to declarations
appearing multiple times.

Fixes: 0eb2a18a ("drm/xe: Implement VM snapshot support for BO's and userptr")
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: <stable@vger.kernel.org> # v6.12+
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250228073058.59510-3-thomas.hellstrom@linux.intel.com