selftests/resctrl: Check for return value after write_schemata()

MBA test case writes schemata but it does not check if the write is
successful or not.

Add the error check and return error properly.

Fixes: 01fee6b ("selftests/resctrl: Add MBA test")
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/resctrl/mba_test.c

@@ -28,6 +28,7 @@ static int mba_setup(int num, ...)
 	struct resctrl_val_param *p;
 	char allocation_str[64];
 	va_list param;
+	int ret;
 
 	va_start(param, num);
 	p = va_arg(param, struct resctrl_val_param *);
@@ -45,7 +46,11 @@ static int mba_setup(int num, ...)
 
 	sprintf(allocation_str, "%d", allocation);
 
-	write_schemata(p->ctrlgrp, allocation_str, p->cpu_no, p->resctrl_val);
+	ret = write_schemata(p->ctrlgrp, allocation_str, p->cpu_no,
+			     p->resctrl_val);
+	if (ret < 0)
+		return ret;
+
 	allocation -= ALLOCATION_STEP;
 
 	return 0;