!2256 MAINTAINERS: update openEuler/MAINTAINERS for UB and PMU

Merge Pull Request from: @mufengyan 
 
hisilicon inclusion
category: doc
bugzilla: https://gitee.com/openeuler/kernel/issues/I838R9



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Add UB drivers and PMU maintainers and documents to
openEuler/MAINTAINERS/

Signed-off-by: Fengyan Mu <mufengyan@hisilicon.com>
 
Link:https://gitee.com/openeuler/kernel/pulls/2256

 

Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>