coresight: etm4x: Add ACPI support in platform driver

Drop ETM4X ACPI ID from the AMBA ACPI device list, and instead just move it
inside the new ACPI devices list detected and used via platform driver.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: linux-acpi@vger.kernel.org
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com> (for ACPI specific changes)
Signed-off-by: Suzuki Poulose <suzuki.poulose@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>