Interface: Rename PSA headers

Renames PSA headers from psa_<api>.h to psa/<api>.h.

Change-Id: I3fc552c39f9a7e6d54e7a7a2f82f076bd03d30a7
Signed-off-by: Jamie Fox <jamie.fox@arm.com>
diff --git a/interface/src/tfm_sst_api.c b/interface/src/tfm_sst_api.c
index 96afadd..34d19fe 100644
--- a/interface/src/tfm_sst_api.c
+++ b/interface/src/tfm_sst_api.c
@@ -5,7 +5,7 @@
  *
  */
 
-#include "psa_protected_storage.h"
+#include "psa/protected_storage.h"
 
 #include "tfm_ns_lock.h"
 #include "tfm_veneers.h"