Fix "taskqgroup_attach: setaffinity failed: 3" with iflib drivers

[shurd]

Summary

Improved logging added in r323879 exposed an error during
attach. We need the irq, not the rid to work correctly. em uses
shared irqs, so it will use the same irq for TX as RX. bnxt does
not use shared irqs, or TX irqs at all, so there's no need to set
the TX irq affinity.

Test Plan

Test with em and bnxt devices to ensure error is corrected
and IRQs have the expected affinity.