[TF-M] Platform: Create platform service for pin functions

Hello, I noticed the merge of this api, which seems require only for platform Musca_a. This create the need to implement dummy functions for the other platform. would it be better to make this configurable for each platform ? I think for the interface connected to platform partition, it is important to have a flexibility. As example some platform , may require an API requesting a pin to be configureable from non secure .

Best regards