Revert "workqueue: remove unused cancel_work()"

Revert "workqueue: remove unused cancel_work()"

[ Upstream commit 73b4b53276a1d6290cd4f47dbbc885b6e6e59ac6 ]

This reverts commit 6417250d3f894e66a68ba1cd93676143f2376a6f.

amdpgu need this function in order to prematurly stop pending
reset works when another reset work already in progress.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Lai Jiangshan<jiangshanlai@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Stable-dep-of: 91d3d149978b ("r8169: prevent potential deadlock in rtl8169_close")
Signed-off-by: Sasha Levin <sashal@kernel.org>