cmd/compile/internal/types: remove misleading comment

The runtime's knowledge of these constants was removed in CL 261364.

Change-Id: I65e5a5ab084c6301eee1c9791bc76df9b824e466
Reviewed-on: https://go-review.googlesource.com/c/go/+/463754
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/src/cmd/compile/internal/types/alg.go b/src/cmd/compile/internal/types/alg.go
index c1f93fc..8d56dec 100644
--- a/src/cmd/compile/internal/types/alg.go
+++ b/src/cmd/compile/internal/types/alg.go
@@ -13,7 +13,6 @@
 //go:generate stringer -type AlgKind -trimprefix A alg.go
 
 const (
-	// These values are known by runtime.
 	ANOEQ AlgKind = iota
 	AMEM0
 	AMEM8