Revert "Bluetooth: btsdio: fix use after free bug in btsdio_remove due to unfinished work"

This reverts commit 1e9ac114.

This patch introduces a possible null-ptr-def problem. Revert it. And the
fixed bug by this patch have resolved by commit 73f7b171 ("Bluetooth:
btsdio: fix use after free bug in btsdio_remove due to race condition").

Fixes: 1e9ac114

 ("Bluetooth: btsdio: fix use after free bug in btsdio_remove due to unfinished work")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>