tty: n_smux: Add/remove platform devices for SSR

Subsystem restart is handled by sending DISCONNECT notifications to
clients.  In addition, a subsystem restart may trigger the mdm helper to
unload the line discipline to capture a memory dump before reloading the
line discipline.  This requires SMUX clients to handle two different
disconnect cases properly.

To converge the two use cases and simplify client code, both a subsystem
restart and line discipline unload will result in removing the platform
devices.  The platform devices are re-added after the line discipline is
loaded or the subsystem restart has been completed.

CRs-Fixed: 386186
Change-Id: Ic61c97acef2a9909f180ac4c81e944351ba9d348
Signed-off-by: Eric Holmberg <eholmber@codeaurora.org>
1 file changed