programs: ssl: Fix printf parameter type cast

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index f92a73e..fc69061 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -3580,7 +3580,7 @@
             ( opt.query_config_mode == DFL_QUERY_CONFIG_MODE ) )
         {
             mbedtls_printf( "Failed to destroy key slot %u - error was %d",
-                            (int) slot, (int) status );
+                            (unsigned) slot, (int) status );
             if( ret == 0 )
                 ret = MBEDTLS_ERR_SSL_HW_ACCEL_FAILED;
         }