irqbalance keeps rechecking IRQ affinity for unchanged IRQs

[StefanBruens]

Even when no IRQ needs rebalancing, irqbalance reads the current affinity mask of (almost) all IRQs on each loop iteration.

This happens as the "info->moved" flag is set at least once during startup, but may not be cleared when "check_affinity" returns no change is necessary. This may also happen later during runtime, when an IRQ is "rebalanced" multiple times during one loop iteration, but ends up with the same mask as before.