coresight: catu: Allow catu drivers to be built as modules

Allow to build coresight-catu as modules, for ease of development.
- Kconfig becomes a tristate, to allow =m
- add catu_remove functions, for module unload
- add a MODULE_DEVICE_TABLE for autoloading on boot

Reviewed-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200928163513.70169-24-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>