USB: document some API requirements on disconnection

USB: document some API requirements on disconnection

A call to usb_set_interface() crashes if the device is deallocated
concurrently, such as due to physical removal or a serious IO error.
It could also interfere with other drivers using the device if the
current driver is unbound before the call is finished.

Document the need to delay driver unbinding until this call returns,
which solves both issues.

Document the same regarding usb_clear_halt(), which is equally known
to be routinely called by drivers.

Explicitly mention finishing pending operations in the documentation
of the driver disconnect callback.

Signed-off-by: Michal Pecio <michal.pecio@gmail.com>
Link: https://lore.kernel.org/r/20240218092515.7635ff8c@foxbook
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>