IB/srp: Allow newline separator for connection string

In case the last argument of the connection string is processed as a
string (destination GID for example).

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Acked-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>