Documentation:Update Documentation/zh_CN/arm64/memory.txt

This is a update of Chinese
documentation:Documentation/zh_CN/arm64/memory.txt

It is based on the modifications of Documentation/arm64/memory.txt in
submission :"e3978cde".

Signed-off-by: Fu Wei <tekkamanninja@gmail.com>
Acked-by: Harry Wei <harryxiyou@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>