[erlang-questions] Change to a more descriptive atom when a crypto algorithm is not supported per FIPS

[Bryan Paxton]

  A few times I have seen a good bit of confusion arise from getting
"notsup" error from the crypto nif in the context of FIPS mode being
enabled and a cryptographic algorithm not allowed in said mode. Thus I
am suggesting that for this case we use "notsup_in_fips_mode"  as a
returnable atom for the error, which I do believe would save people time
when grokking the situation the ambiguous error. 

 I'd  be glad to do a PR for this and almost started on such but figured
it best to check here before so.

--

Bryan Paxton