This should be called by a parallel port device driver that
has registered itself using parport_register_driver
when it
is about to be unloaded.
When it returns, the driver's attach
routine will no longer
be called, and for each port that attach
was called for, the
detach
routine will have been called.
If the caller's attach
function can block, it is their
responsibility to make sure to wait for it to exit before
unloading.
All the driver's detach
calls are guaranteed to have
finished by the time this function returns.
The driver's detach
call is not allowed to block.