Use task_pid_nr() in ip_vs_sync.c

The sync_master_pid and sync_backup_pid are set in set_sync_pid() and are
used later for set/not-set checks and in printk.  So it is safe to use the
global pid value in this case.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>