vfio/mlx5: Refactor the SAVE callback to activate a work only upon an error

Upon a successful SAVE callback there is no need to activate a work, all
the required stuff can be done directly.

As so, refactor the above flow to activate a work only upon an error.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20230911093856.81910-4-yishaih@nvidia.com


Signed-off-by: Alex Williamson <alex.williamson@redhat.com>