Dynamically adds sysfs attributes for all connections defined in the CTI.

Each connection has a triggers<N> sub-directory with name, in_signals,
in_types, out_signals and out_types as read-only parameters in the
directory. in_ or out_ parameters may be omitted if there are no in or
out signals for the connection.

Additionally each device has a nr_cons in the connections sub-directory.

This allows clients to explore the connection and trigger signal details
without needing to refer to device tree or specification of the device.

Standardised type information is provided for certain common functions -
e.g. snk_full for a trigger from a sink indicating full. Otherwise type
defaults to genio.
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200320165303.13681-10-mathieu.poirier@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>