[llvm] [RISCV] Move ActiveElementsAffectResult to TSFlags. NFC (PR #101123)

[Philip Reames via llvm-commits]

preames wrote:

High level question here.  Why store the new TSFlag on the *pseudo* instead of the underlying *instruction*?  We can go from the former to the later easily for lookup purposes.  This seems like a property of the instruction, not of a particular pseudo which wraps it.  

https://github.com/llvm/llvm-project/pull/101123