Update ONOS behaviors to work with chip-independent pipeconf

[ccascone]

Even if the P4 program is now chip-independent (#40), we still produce to pipeconf IDs for the different Tofino chip types (montara, mavericks) since some behaviors depend on the pipeconf ID to decide which entries to insert (e.g., for the switch_info table, or INT mirroring sessions).

The plan is to update the behaviors to avoid depending on the pipeconf ID, but instead, retrieve the chip-type via gNMI. This might require support in ONOS core drivers.