crypto: only try to set FIPS mode if different

Turning FIPS mode on (or off) when it's already on (or off) should be a
no-op, not an error.

PR-URL: https://github.com/nodejs/node/pull/12210
Fixes: https://github.com/nodejs/node/issues/11849


Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>