cmd/compile: rotate phase's title 180 degrees in ssa/html.go
Modify phase's title according to html.go:122 TODO.
Fixes #41098
Change-Id: I58fa365e718600aaaa0a72cce72d35a484cde8b8
Reviewed-on: https://go-review.googlesource.com/c/go/+/251657
Reviewed-by: Bradford Lamson-Scribner <brad.lamson@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Josh Bleecher Snyder <josharian@gmail.com>