Updates the STM driver to use the trace ID allocation API.
This uses the _system_id calls to allocate an ID on device poll,
and release on device remove.

The sysfs access to the STMTRACEIDR register has been changed from RW
to RO. Having this value as writable is not appropriate for the new
Trace ID scheme - and had potential to cause errors in the previous
scheme if values clashed with other sources.
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230116124928.5440-5-mike.leach@linaro.org