RDMA/mlx5: Drop redundant work canceling from clean_keys()

The canceling of dealyed work in clean_keys() is a leftover from years
back and was added to prevent races in the cleanup process of MR cache.
The cleanup process was rewritten a few years ago and the canceling of
delayed work and flushing of workqueue was added before the call to
clean_keys().

Signed-off-by: Michael Guralnik <michaelgur@nvidia.com>
Link: https://patch.msgid.link/943d21f5a9dba7b98a3e1d531e3561ffe9745d71.1725362530.git.leon@kernel.org


Signed-off-by: Leon Romanovsky <leon@kernel.org>