panvk: free up hwvulkan_device_t upon driver unloading

Per <hardware/hwvulkan.h>, the hw_device_t::close() function is called
upon driver unloading. The behavior has been like this since Android 10.

Reviewed-by: Mary Guillemard <mary.guillemard@collabora.com>
Acked-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35561>

src/panfrost/vulkan/panvk_android.c

@@ -72,6 +72,11 @@ panvk_hal_open(const struct hw_module_t *mod, const char *id,
 static int
 panvk_hal_close(struct hw_device_t *dev)
 {
-   /* hwvulkan.h claims that hw_device_t::close() is never called. */
-   return -1;
+   /* the hw_device_t::close() function is called upon driver unloading */
+   assert(dev->version == HWVULKAN_DEVICE_API_VERSION_0_1);
+   assert(dev->module == &HAL_MODULE_INFO_SYM.common);
+
+   hwvulkan_device_t *hal_dev = container_of(dev, hwvulkan_device_t, common);
+   free(hal_dev);
+   return 0;
 }