[llvm] [RISCV] Add getJumpConditionMergingParams to support branch condition merging (PR #206897)

[Yingying Wang via llvm-commits]

buggfg wrote:

With this PR, the SPEC CPU2006 FP geomean improves by approximately 1% on the XuanTie C920, while the INT geomean remains essentially unchanged.

https://github.com/llvm/llvm-project/pull/206897