Revert "firewire: core: move workqueue handler from 1394 OHCI driver to core function"

This reverts commit 767bfb9ef27ebf760290d9f8bc303828b018c312. It appears
that the call of ohci_flush_iso_completions() in the work item scheduled
by hardIRQ of 1394 OHCI for any isochronous context changes the timing to
queue events in the view of user space application.

Link: https://lore.kernel.org/r/20240912133038.238786-3-o-takashi@sakamocchi.jp


Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>