IB/iser: centralize setting desc type and done callback

Move this common logic into iser_create_send_desc instead of duplicating
the code.

Reviewed-by: Sergey Gorenko <sergeygo@nvidia.com>
Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Link: https://lore.kernel.org/r/20230330131333.37900-2-mgurtovoy@nvidia.com


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