ila: Fix rhashtable walker list corruption

ila: Fix rhashtable walker list corruption

BugLink: https://bugs.launchpad.net/bugs/1823060
[ Upstream commit b5f9bd15b88563b55a99ed588416881367a0ce5f ]

ila_xlat_nl_cmd_flush uses rhashtable walkers allocated from the
stack but it never frees them.  This corrupts the walker list of
the hash table.

This patch fixes it.

Reported-by: syzbot+dae72a112334aa65a159@syzkaller.appspotmail.com
Fixes: b6e71bdebb12 ("ila: Flush netlink command to clear xlat...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>