IB/iser: open code iser_conn_state_comp_exch

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

Acked-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Sergey Gorenko <sergeygo@nvidia.com>
Link: https://lore.kernel.org/r/20221016093833.12537-2-mgurtovoy@nvidia.com


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