Maintainers.txt: Update the name of 'Hao Wu' to 'Hao A Wu'

This commit will update the name of 'Hao Wu' to 'Hao A Wu' to match the
mail address.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Hao A Wu <hao.a.wu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>