[llvm] [RISCV] Remove duplicate WriteRes<WriteJalr for MIPSP8700. (PR #123865)

[Pengcheng Wang via llvm-commits]

wangpc-pp wrote:

> > (Actually I think the latency of jal/jalr doesn't matter at all, since they are scheduling boundaries anyway.)
> 
> What about llvm-mca?

llvm-mca assumes the latency is 100 (can be specified via `-call-latency` option) for instructions with `isCall = 1`:
https://github.com/llvm/llvm-project/blob/7c58d6363a40fc6d1cdf6a147da8f3bb0d4f96ec/llvm/lib/MCA/InstrBuilder.cpp#L222-L237

And I just found that we don't set `isCall = 1` to JAL/JALR, is this by design?

https://github.com/llvm/llvm-project/pull/123865