IB/srp: Stop the scsi_eh_<n> and scsi_tmf_<n> threads if login fails

scsi_host_alloc() not only allocates memory for a SCSI host but also
creates the scsi_eh_<n> kernel thread and the scsi_tmf_<n> workqueue.
Stop these threads if login fails by calling scsi_host_put().

Reported-by: Konstantin Krotov <kkv@clodo.ru>
Fixes: fb49c8bb

 ("Remove an extraneous scsi_host_put() from an error path")
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: Sebastian Parschauer <sebastian.riemer@profitbricks.com>
Cc: <stable@vger.kernel.org> #v3.19
Signed-off-by: Doug Ledford <dledford@redhat.com>