[RISCV] Add new SchedRead SchedWrite

The patch fixes some typos and introduces ReadFMemBase, ReadFSGNJ32,
ReadFSGNJ64, WriteFSGNJ32, WriteFSGNJ64, ReadFMinMax32, ReadFMinMax64,
WriteFMinMax32, WriteFMinMax64, so the target CPU with different pipeline model
could use them to describe latency.

Differential Revision: https://reviews.llvm.org/D75515