[PATCH] eal/riscv: implement prefetch using __builtin_prefetch

[sunyuechi]

Hi,

In the previous prefetch discussion:

"Let's hope you get such hardware by the next release. We will need 
reviews too."

https://inbox.dpdk.org/dev/CAJFAV8zatWiYQoe4kETcM61=OS1k=QaPRsNjYSYDspKC+voiQw@mail.gmail.com/

Could you share your test environment and results?

And DPDK requires a real name in the Signed-off-by line.