[llvm] [RISCV] Re-format RISCVFeatures.td so it doesn't look like AssemblerPredicate is an operand to Predicate. (PR #79076)

[Wang Pengcheng via llvm-commits]

https://github.com/wangpc-pp approved this pull request.

LGTM with nits.

https://github.com/llvm/llvm-project/pull/79076