[llvm] [RISCV][TTI] Implement getAddressComputationCost() in RISCV TTI. (PR #149955)

[Elvis Wang via llvm-commits]

https://github.com/ElvisWang123 commented:

Move  the address computation cost to `getAddressComputationCost`. 

Some of the LV tests changes seems can prevent. 
I will try to optimize the gather/scatter with uniform address to masked load/store in LV if possible.

https://github.com/llvm/llvm-project/pull/149955