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/include/tfm_api.h b/interface/include/tfm_api.h
index 8e152ff..5a56ec7 100644
--- a/interface/include/tfm_api.h
+++ b/interface/include/tfm_api.h
@@ -13,7 +13,7 @@
 #endif
 
 #include <stdint.h>
-#include "psa_client.h"
+#include "psa/client.h"
 
 #define TFM_INVALID_CLIENT_ID 0