firewire: ohci: remove obsolete module-level debug parameter

The module-level debug parameter was added in v2.6.26 by a commit
ad3c0fe8 ("firewire: debug interrupt events"). Its functionality
has long been superseded by tracepoints.

This commit removes the module parameter, bye.

Link: https://lore.kernel.org/r/20250821003017.186752-5-o-takashi@sakamocchi.jp


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