soundwire: stream: fix out of boundary access on port properties

Assigning local iterator to array element and using it again for
indexing would cross the array boundary.
Fix this by directly referring array element without using the local
variable.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>