fabrics: support fabrics sq flow control disable

fabrics: support fabrics sq flow control disable

If the discovery log entry indicates that the subsystem supports
disabling sq flow control, we ask the host to connect and disable sq
flow control (omit sq_head pointer updates). Also add a connect option
to explicitly ask for disable_sqflow.

If we failed to add_ctrl in connect-all command, we retry without it
to be backward compatible with a driver that cannot accept the new
flag.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>