Multithreaded IRQ handler processing

[Deniz-Eren]

During the process of harmonizing with Linux Kernel version 6.6 (#52), it was discovered Linux has gone down the direction of supporting multiple threads to process IRQ handlers.

Currently this capability isn't seen as necessary, however would be a good enhancement.

When implementing this feature functions netif_tx_lock and netif_tx_unlock need to be implemented, together with refactoring of the current IRQ processing algorithms.

We may need to review our handling of spin_lock_irqsave and spin_unlock_irqrestore when implementing multithread IRQ support.