[compiler-rt] [RISCV][compiler-rt] Small fixes for __riscv_feature_bits (PR #100158)

[Philip Reames via llvm-commits]

https://github.com/preames approved this pull request.

LGTM

JFYI, since this seems to be textually the same as the final iteration on my review, I'm going to treat you posting this as an approval on that one.  I don't care which one lands.  I'm about to run out for an errand, and if this hasn't landed by the time I take another look this afternoon I'll land one or the other.

https://github.com/llvm/llvm-project/pull/100158