zdtm: make zdtm to not fail if time changed in fd-list

In case if time is modified in ls -l output we should
not treat it as error, interrupting zdtm work

-lrwx------ 1 root root 64 Feb 17 14:52 0 -> /dev/null
-lrwx------ 1 root root 64 Feb 17 14:52 1 -> /dev/null
-lrwx------ 1 root root 64 Feb 17 14:52 2 -> /dev/null
+lrwx------ 1 root root 64 Feb 17 14:53 0 -> /dev/null
+lrwx------ 1 root root 64 Feb 17 14:53 1 -> /dev/null
+lrwx------ 1 root root 64 Feb 17 14:53 2 -> /dev/null

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>