go/common/crypto/mrae/deoxysii: Use SHA512/256 for the KDF

[Yawning]

Following 73aacaa, this should also use
the correct hash algorithm for the KDF.

[codecov]

Codecov Report

Merging #2853 into master will decrease coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2853      +/-   ##
==========================================
- Coverage   67.38%   67.33%   -0.05%     
==========================================
  Files         344      344              
  Lines       33406    33406              
==========================================
- Hits        22509    22495      -14     
- Misses       7998     8007       +9     
- Partials     2899     2904       +5     

Impacted Files	Coverage Δ
go/common/crypto/mrae/deoxysii/asymmetric.go	81.81% <100.00%> (ø)
go/consensus/tendermint/apps/roothash/query.go	64.70% <0.00%> (-11.77%)	⬇️
go/consensus/tendermint/abci/state/state.go	50.00% <0.00%> (-7.70%)	⬇️
go/common/cbor/codec.go	77.14% <0.00%> (-5.72%)	⬇️
go/worker/common/p2p/p2p.go	61.71% <0.00%> (-4.51%)	⬇️
go/runtime/committee/nodes.go	80.39% <0.00%> (-3.93%)	⬇️
.../consensus/tendermint/apps/roothash/state/state.go	68.62% <0.00%> (-3.93%)	⬇️
go/staking/api/grpc.go	52.61% <0.00%> (-0.99%)	⬇️
go/storage/client/client.go	77.09% <0.00%> (-0.89%)	⬇️
go/consensus/tendermint/abci/state.go	69.11% <0.00%> (-0.78%)	⬇️
... and 11 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6f0430d...f12232a. Read the comment docs.