On AMD/ATI controllers, the HD-audio controller driver allows a bus
reset upon the error recovery, and its procedure includes the
cancellation of pending jack polling work as found in
snd_hda_bus_codec_reset().  This works usually fine, but it becomes a
problem when the reset happens from the jack poll work itself; then
calling cancel_work_sync() from the work being processed tries to wait
the finish endlessly.

As a workaround, this patch adds the check of current_work() and
applies the cancel_work_sync() only when it's not from the
jackpoll_work.

This doesn't fix the root cause of the reported error below, but at
least, it eases the unexpected stall of the whole system.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200937
Cc: <stable@vger.kernel.org>
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>