iscsi-target: use strlcpy in iscsit_collect_login_stats

last_intr_fail_name is a fixed-size array and could theoretically
overflow.  In reality intrname->value doesn't seem to depend on
untrusted input or be anywhere near 224 characters, so the overflow is
pretty theoretical.  But strlcpy is cheap enough.

Found by coverity.

Signed-off-by: Joern Engel <joern@logfs.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>