IB/srp: Get rid of extra scsi_host_put()s if reconnection fails

If a reconnection attempt fails, then SRP does two scsi_host_put()s.
This is a historical relic from an earlier version of the driver that
took a reference on the scsi_host before trying to reconnect, so get
rid of the extra scsi_host_put().

Signed-off-by: Roland Dreier <rolandd@cisco.com>