library/tests: replace md_psa.h with psa_util.h as include file for MD conversion

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/tests/suites/test_suite_pk.function b/tests/suites/test_suite_pk.function
index 226598c..f054443 100644
--- a/tests/suites/test_suite_pk.function
+++ b/tests/suites/test_suite_pk.function
@@ -16,7 +16,7 @@
  * but the test code generator requires test case data to be valid C code
  * unconditionally (https://github.com/Mbed-TLS/mbedtls/issues/2023). */
 #include "psa/crypto.h"
-#include "md_psa.h"
+#include "mbedtls/psa_util.h"
 
 /* Used for properly sizing the key buffer in pk_genkey_ec() */
 #include "psa_util_internal.h"