IB/srpt: Fix srpt_cm_req_recv() error path (1/2)

Once a target session has been allocated, if an error occurs, the session
must be freed. Since it is not safe to call blocking code from the context
of an connection manager callback, trigger target session release in this
case by calling srpt_close_ch().

Fixes: db7683d7

 ("IB/srpt: Fix login-related race conditions")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>