soundwire: cadence/intel: simplify PDI/port mapping

soundwire: cadence/intel: simplify PDI/port mapping

The existing Linux code uses a 1:1 mapping between ports and PDIs, but
still has an independent allocation of ports and PDIs.

Let's simplify the code and remove the port layer by only using PDIs.

This patch does not change any functionality, just removes unnecessary
code.

This will also allow for further simplifications where the PDIs are
not dynamically allocated but instead described in a topology file.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20190916192348.467-5-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>