Illumos#16463 zfs_ioc_recv leaks nvlist

In https://www.illumos.org/issues/16463 it was observed that
an nvlist was being leaked in zfs_ioc_recv() due a missing
call to nvlist_free for "hidden_args".
For OpenZFS the same issue exists in zfs_ioc_recv_new() and
is addressed by this PR.

This change also properly frees nvlists in the unlikely
event that a call to get_nvlist() fails.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Signed-off-by: Andy Fiddaman <illumos@fiddaman.net>
Closes #16077