arm64/mpam: Fix uninitialized symbol ret

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8EF0Z



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This fix compile error:

arch/arm64/kernel/mpam/mpam_ctrlmon.c:793
resctrl_mkdir_mondata_all_subdir() error: uninitialized symbol 'ret'.

Fixes: 037915d2 ("arm64/mpam: resctrl: Remove ctrlmon sysfile")
Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>