[AMDGPU] Improve code size cost model (part 2)

Summary: Added estimations for ShuffleVector, some cast and arithmetic instructions

Reviewers: rampitec

Reviewed By: rampitec

Subscribers: arsenm, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, hiraditya, zzheng, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69629