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

stable inclusion
from stable-v5.10.180
commit 0c29f14cf470ce7e7fe85eb25602bb138b871256
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8DDFN

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0c29f14cf470ce7e7fe85eb25602bb138b871256



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[ Upstream commit 0d45c83b ]

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: 01fee6b4 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>