dt-bindings: arm: Adds CoreSight CTI hardware definitions

Adds new coresight-cti.yaml file describing the bindings required to define
CTI in the device trees.

Adds an include file to dt-bindings/arm to define constants describing
common signal functionality used in CoreSight and generic usage.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200320165303.13681-6-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>