clocksource: sh_cmt: Replace global spinlock with a per-device spinlock
clocksource: sh_cmt: Replace global spinlock with a per-device spinlock

The global spinlock is used to protect the shared start/stop register.
Now that all CMT channels are handled by a single device instance, use a
per-device spinlock.

Signed-off-by: Laurent Pinchart <ae960578cc5eca7b9b1dbc37d9caa6cb634f35e0@ideasonboard.com>
Tested-by: Simon Horman <9662bddcc379be37df16f02a449c344b4718c1a1@verge.net.au>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs