Revert "Bluetooth: Shutdown controller after workqueues are flushed or cancelled"

This reverts commit 5d16a828 which is
commit 0ea9fd00

 upstream.

It has been reported to have problems:
	https://lore.kernel.org/linux-bluetooth/8735ryk0o7.fsf@baylibre.com/

Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Sasha Levin <sashal@kernel.org>
Link: https://lore.kernel.org/r/efee3a58-a4d2-af22-0931-e81b877ab539@roeck-us.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>