Do not insert twice for first filter
Do not insert twice for first filter

On the first call, the filter list is empty,
the element will be insert two times, just return after the first insert.

Tested:
Check the filter callback functions, there is no duplicated call;

Signed-off-by: Yong Li <88803ad297965b86eb60f441534f52cc3a2b6651@linux.intel.com>
Change-Id: I4e4d5147b5c0466b651700f79afcb34940e6f48a

openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid,openbmc/phosphor-host-ipmid