n_smux: smux_ctl: Disable local loopback

For development, the local loopback mode was used.  Now that
the full system is ready, disable loopback mode to enable
communication with the remote system.

Change-Id: I24bee29b3fa41690ccbaf8992ecb3cb166dc3ffc
Signed-off-by: Eric Holmberg <eholmber@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>