eventpoll: parse_fdinfo_pid_s() returns allocated object for eventpol tfd

We are going to collect all objects in a list and write them into
the eventpoll image. The eventpoll tfd image will be depricated.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>