netipmid: Remove unused event references

Now that all the provider libraries are only loaded by the main ipmid
queue, there are no callers for the event object, so it can be removed.
The same goes for the event loop; all users of the sd_event object have
been replaced with boost::asio, so it can be removed.

Change-Id: Id271c4960a2c5386d6163cc9baecdc368e5e328f
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
3 files changed