Add guards for mbedtls_psa_crypto_free()

Signed-off-by: Przemek Stekiel <przemyslaw.stekiel@mobica.com>
diff --git a/programs/fuzz/fuzz_privkey.c b/programs/fuzz/fuzz_privkey.c
index e51ee30..d1da589 100644
--- a/programs/fuzz/fuzz_privkey.c
+++ b/programs/fuzz/fuzz_privkey.c
@@ -71,9 +71,11 @@
             abort();
         }
     }
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
 exit:
-    mbedtls_pk_free(&pk);
     mbedtls_psa_crypto_free();
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+    mbedtls_pk_free(&pk);
 #else
     (void) Data;
     (void) Size;