etnaviv: fix leak of the screen hash table

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Tested-by: Philipp Zabel p.zabel@pengutronix.de
Reviewed-by: Simon Ser <contact@emersion.fr>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12904>

src/gallium/winsys/etnaviv/drm/etnaviv_drm_winsys.c

@@ -142,6 +142,11 @@ etna_drm_screen_destroy(struct pipe_screen *pscreen)
    if (destroy) {
       int fd = etna_device_fd(screen->dev);
       _mesa_hash_table_remove_key(fd_tab, intptr_to_pointer(fd));
+
+      if (!fd_tab->entries) {
+         _mesa_hash_table_destroy(fd_tab, NULL);
+         fd_tab = NULL;
+      }
    }
    mtx_unlock(&etna_screen_mutex);