coresight: debug: Move ACPI support from AMBA driver to platform driver

Add support for the cpu debug devices in a new platform driver, which can
then be used on ACPI based platforms. This change would now allow runtime
power management for ACPI based systems. The driver would try to enable
the APB clock if available.

Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: James Clark <james.clark@arm.com>
Cc: linux-acpi@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: coresight@lists.linaro.org
Acked-by: Sudeep Holla <sudeep.holla@arm.com> # For ACPI related changes
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>