[llvm] [RISCV] Lower f16/bf16 splat_vector by bitcasting to i16 instead of promoting to f16. (PR #108298)

[Luke Lau via llvm-commits]

https://github.com/lukel97 commented:

Should the PR title say "instead of promoting to f32"?

https://github.com/llvm/llvm-project/pull/108298