IB/iser: open code iser_disconnected_handler

There is a single caller to iser_disconnected_handler. Open code its
logic and remove it.

Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Link: https://lore.kernel.org/r/20221016093833.12537-4-mgurtovoy@nvidia.com


Reviewed-by: Sergey Gorenko <sergeygo@nvidia.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Leon Romanovsky <leon@kernel.org>