[PATCH] eal: add support for TRNG with Arm RNG feature

[Wathsala Wathawana Vithanage]

> If your patch are to have non-zero chance of being accepted, it should include
> a base implementation based on getrandom() (and the Windows equivalent),
> with the proper optimizations (e.g., batching entropy requests to the kernel
> on a per-lcore basis).
> 
> You would also need to provide a rationale why ARM CPU HW random
> numbers are better than what the kernel can offer. The only potential reason I
> can think of is performance, so you would need to quantify that in some way.
> 
> In addition, reliance on CPU CSRNG would need to be a build-time option, and
> disabled by default.
> 
> Plus, what I've mentioned several times, give a rationale why DPDK should
> have this functionality.
> 

Thank you for the clarification. If I understood correctly following is what's needed.

1- An implementation of rte_csrand that calls getrandom() with per-core entropy caching. Which will be the default for DPDK.
2- Build time flag to enable HW CSRNG for those who want to override the default kernel getrandom() feature. 
3- Rationale for why CPU HW CSRNG is required.

To elaborate on Item 3, the rationale is simple, we want to enable the HW feature for those who need it.