clockevents/drivers/sh_cmt: Migrate to new 'set-state' interface

clockevents/drivers/sh_cmt: Migrate to new 'set-state' interface

Migrate sh_cmt driver to the new 'set-state' interface provided by
clockevents core, the earlier 'set-mode' interface is marked obsolete
now.

This also enables us to implement callbacks for new states of clockevent
devices, for example: ONESHOT_STOPPED.

Cc: Magnus Damm <[email protected]>
Cc: Laurent Pinchart <[email protected]>
Cc: Paul Mundt <[email protected]>
Signed-off-by: Viresh Kumar <[email protected]>
Signed-off-by: Daniel Lezcano <[email protected]>
Acked-by: Laurent Pinchart <[email protected]>