MAINTAINERS: remove Xavier as maintainer of HISILICON ROCE DRIVER

Wei Hu(Xavier) has left Hisilicon and his email address is invalid now.
I'd be glad to add him back with another address if he wants to continue
maintain this module.

Link: https://lore.kernel.org/r/1617007584-39842-1-git-send-email-liweihang@huawei.com


Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>