dh_client.c: modify prompt message

Signed-off-by: Yanray Wang <yanray.wang@arm.com>
diff --git a/programs/pkey/dh_client.c b/programs/pkey/dh_client.c
index 0d4172b..08eb549 100644
--- a/programs/pkey/dh_client.c
+++ b/programs/pkey/dh_client.c
@@ -60,7 +60,7 @@
 #elif defined(MBEDTLS_BLOCK_CIPHER_NO_DECRYPT)
 int main(void)
 {
-    mbedtls_printf("MBEDTLS_BLOCK_CIPHER_NO_DECRYPT implicitly defined.\n");
+    mbedtls_printf("MBEDTLS_BLOCK_CIPHER_NO_DECRYPT defined.\n");
     mbedtls_exit(0);
 }
 #else