- These functions are used both in pkparse.c for key parsing
as well as pk.c for managing copy_from_psa(). As as consequence
they should belong to pk.c, but that would make that module
messier, so that's why a new separate module is added.
- Their guard can be changed from PKPARSE_C to PK_C.
Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>