bgpd: Don't lookup paf structure get straight to the point

bgpd: Don't lookup paf structure get straight to the point

The paf data structure is stored based upon an internal
bgp enum.  The code is looking over all AFI/SAFI's and
doing a paf_af_find which then calls afindex to find
the right paf structure.  Let's just loop over the
peer->peer_af_array[] and cut straight to the chase.
Under some loads the paf_af_find was taking up 6%
of the run time.  This removes it entirely.

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