staging: r8188eu: use a delayed worker for led updates

staging: r8188eu: use a delayed worker for led updates

The led layer uses a combination of timer and worker for periodic led
updates, e.g. for blinking. The reason seems to be that blocking
operations like a usb read are not allowed in a timer handler.

Replace the combination of timer and worker with a delayed worker.

Convert the timeout defines from milliseconds to jiffies to make them
usable as delays for the delayed worker. Shorten the names of the defines
and rename the work item to make checkpatch happy.

Other layers may call SwLedControlMode1 to update the led state. Such
an update may result in cancelling the delayed worker. SwLedControlMode1
might be called in interrupt context, we must use cancel_delayed_work to
cancel the worker. cancel_delayed_work_sync waits until the worker is
finished, this is not allowed in interrupt context.

DeInitLed871x is called when the driver is removed or when the system
goes into standby. We may use cancel_delayed_work_sync here to cancel
the delayed worker.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20211126114135.18228-1-martin@kaiser.cx
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>