coresight: catu: Introduce refcount and spinlock for enabling/disabling

coresight: catu: Introduce refcount and spinlock for enabling/disabling

When tracing ETM data on multiple CPUs concurrently via the
perf interface, the CATU device is shared across different CPU
paths. This can lead to race conditions when multiple CPUs attempt
to enable or disable the CATU device simultaneously.

To address these race conditions, this patch introduces the
following changes:

1. The enable and disable operations for the CATU device are not
   reentrant. Therefore, a spinlock is added to ensure that only
   one CPU can enable or disable a given CATU device at any point
   in time.

2. A reference counter is used to manage the enable/disable state
   of the CATU device. The device is enabled when the first CPU
   requires it and is only disabled when the last CPU finishes
   using it. This ensures the device remains active as long as at
   least one CPU needs it.

Fixes: fcacb5c154ba ("coresight: Introduce support for Coresight Address Translation Unit")
Signed-off-by: Yabin Cui <yabinc@google.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Reviewed-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250429231301.1952246-2-yabinc@google.com