log: Disable the syslog driver by default

This driver interferes with other sandbox tests since it causes log output
to be interspersed with "No ethernet found." messages. Disable this driver
by default.

Enable it for the syslog tests so that they still pass.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/log/syslog_test_ndebug.c b/test/log/syslog_test_ndebug.c
index 7815977..c7f5a60 100644
--- a/test/log/syslog_test_ndebug.c
+++ b/test/log/syslog_test_ndebug.c
@@ -33,6 +33,7 @@
 	int old_log_level = gd->default_log_level;
 	struct sb_log_env env;
 
+	ut_assertok(syslog_test_setup(uts));
 	gd->log_fmt = LOGF_TEST;
 	gd->default_log_level = LOGL_INFO;
 	env_set("ethact", "eth@10002000");
@@ -49,6 +50,7 @@
 	ut_assertnonnull(env.expected);
 	gd->default_log_level = old_log_level;
 	gd->log_fmt = log_get_default_format();
+	ut_assertok(syslog_test_finish(uts));
 
 	return 0;
 }