Add support for configuring IRQ affinity for network interfaces via
systemd .link files. For now, the new IRQAffinityPolicy= option in the [Link]
section only accepts "single", which pins all MSI IRQs to CPU 0.
This allows declarative IRQ affinity configuration for network devices
during udev processing, which is useful for optimizing network
performance on multi-core systems.
Further commits will expand the options supported by IRQAffinityPolicy=.
Quentin Deslandes
66892d877c