math: remove riscv64 assembly implementations of rounding
Fixes #68322
This reverts commit
ad377e906a8ee6f27545d83de280206dacec1e58.
Change-Id: Ifa4811e2c679d789cc830dbff5e50301410e24d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/596516
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Commit-Queue: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>