bgpd: Call the new doppelganger connection incoming

bgpd: Call the new doppelganger connection incoming

In bgp_accept, the newly created doppelganger is
accepting a connection and setting it up to work
properly.  For this incoming connection let's call
it incoming as well.

Author's Note:  I am changing the bgp_accept function
in this manner because I find it incredibly confusing
remembering what is what direction and all my other
attempts at getting this straight has caused real
problems.  So I am resorting to doing really small
transformational changes at a time.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>