all: enable FIPS verification code

all: enable FIPS verification code

Previous CLs committed changes to cmd/compile, cmd/link,
and crypto/internal/fips/check behind boolean flags.
Turn those flags on, to enable the CLs.

This is a separate, trivial CL for easier rollback.

For #69536.

Change-Id: I68206bae0b7d7ad5c8758267d1a2e68853b63644
Reviewed-on: https://go-review.googlesource.com/c/go/+/626000
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>