bpf, devmap: Add missing bulk queue free

dev_map_free() forgot to free bulk queue when freeing its entries.

Fixes: 5d053f9d

 ("bpf: devmap prepare xdp frames for bulking")
Signed-off-by: Toshiaki Makita <toshiaki.makita1@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>