tools: ynl: use ynl_sock_read_msgs() for ACK handling

ynl_recv_ack() is simple and it's the only user of mnl_cb_run().
Now that ynl_sock_read_msgs() exists it's actually less code
to use ynl_sock_read_msgs() instead of being special.

Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Link: https://lore.kernel.org/r/20240227223032.1835527-10-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>