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

Add support for the stm devices in the 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: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.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
Cc: linux-stm32@st-md-mailman.stormreply.com
Tested-by: Sudeep Holla <sudeep.holla@arm.com> # Boot and driver probe only
Acked-by: Sudeep Holla <sudeep.holla@arm.com> # For ACPI related changes
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>