bridge: Get rid of bridge_get_all_ifaces(), bridge_fetch_dp_ifaces().

bridge: Get rid of bridge_get_all_ifaces(), bridge_fetch_dp_ifaces().

The bridge_get_all_ifaces() function is rather odd.  It creates an shash
index over the "struct iface"s within a bridge, but there's already an
index over them (the 'iface_by_name' hmap in struct bridge) that the
iface_lookup() function searches.  The only value it adds is to put the
names of bond fake ifaces into the index, but that's hardly worth it.  We
can just search the existing hash table as needed, instead.

The bridge_fetch_dp_ifaces() function is also odd.  It fetches the entire
mapping from port number to name from the dpif again, although this has
already been done twice already.  We can just merge this in with the second
iteration.

This commit makes both of those changes.