cursor-renderer/native: Clear GPU state before closing device

This ensures we don't have any left over cursor GPU buffers (via
gbm_bo's) after destroying the corresponding gbm_device (owned by
MetaRenderDevice).

Fixes crashes with backtraces such as

  1) meta_drm_buffer_gbm_finalize at ../src/backends/native/meta-drm-buffer-gbm.c:450
  4) invalidate_cursor_gpu_state at ../src/backends/native/meta-cursor-renderer-native.c:1167
  9) update_cursor_sprite_texture at ../src/wayland/meta-wayland-cursor-surface.c:70
 10) meta_wayland_surface_role_apply_state at ../src/wayland/meta-wayland-surface.c:1869
 11) meta_wayland_surface_apply_state at ../src/wayland/meta-wayland-surface.c:832
 12) meta_wayland_surface_commit at ../src/wayland/meta-wayland-surface.c:993
 13) wl_surface_commit at ../src/wayland/meta-wayland-surface.c:1158
 14) ffi_call_unix64 at ../src/x86/unix64.S:76
 15) ffi_call at ../src/x86/ffi64.c:525

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2147>
(cherry picked from commit 4159c76a)