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/platform/include/tfm_platform_system.h b/platform/include/tfm_platform_system.h
index c248fe5..c297d3b 100644
--- a/platform/include/tfm_platform_system.h
+++ b/platform/include/tfm_platform_system.h
@@ -12,7 +12,7 @@
  *       target.
  */
 
-#include "psa_client.h"
+#include "psa/client.h"
 #include "tfm_plat_defs.h"
 #include "tfm_platform_api.h"