v3dv/bo: reset bo and then call gem close
After 'v3dv: fix debug dump on BO free' we changed the order, and this lead to the following test dEQP-VK.api.object_management.multithreaded_per_thread_resources.device_memory_small
Raising this assertion: deqp-vk: ../src/broadcom/vulkan/v3dv_bo.c:281: v3dv_bo_alloc: Assertion `bo && bo->handle == 0' failed.
Fixes: 2c445971 ('v3dv: fix debug dump on BO free')