target: don't always say "ipv6" as address type

"lstat->last_intr_fail_ip_addr" is an array inside the "lstat" struct.
It's never NULL so we always print "ipv6\n" here.  The test should be
"if (lstat->last_intr_fail_ip_family == AF_INET6)".

We don't need the temporary buffer either.  We could print directly into
"page".

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>