Rationalize includes in psa_util

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/library/psa_util_internal.h b/library/psa_util_internal.h
index 74276d5..18bdc9e 100644
--- a/library/psa_util_internal.h
+++ b/library/psa_util_internal.h
@@ -26,6 +26,8 @@
 /* Include the public header so that users only need one include. */
 #include "mbedtls/psa_util.h"
 
+#include "psa/crypto.h"
+
 #if defined(MBEDTLS_PSA_CRYPTO_C)
 
 /*************************************************************************