util: fix comment typos

When the deep(Strict)Equal comparison functions were moved to an
internal module, a variable named `current` was replaced with `val1`.
That accidentally also replaced a few "currently"s in comments.

Refs: https://github.com/nodejs/node/pull/16084

PR-URL: https://github.com/nodejs/node/pull/21436


Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>