vulkan: Add missing va_end

Fix defect reported by Coverity Scan.

Missing varargs init or cleanup (VARARGS)
missing_va_end: va_end was not called for ap.

Fixes: f8b584d6a5 ("vulkan/runtime,radv: Add shared BVH building framework")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32858>

src/vulkan/runtime/vk_acceleration_structure.c

@@ -462,8 +462,10 @@ vk_accel_struct_cmd_begin_debug_marker(VkCommandBuffer commandBuffer,
    va_start(ap, format);
 
    char *name;
-   if (vasprintf(&name, format, ap) == -1)
+   if (vasprintf(&name, format, ap) == -1) {
+      va_end(ap);
       return;
+   }
 
    va_end(ap);