crypto: make update(buf, enc) ignore encoding

Make the cipher/decipher/hash/hmac update() methods ignore the input
encoding when the input is a buffer.

This is the documented behavior but some inputs were rejected, notably
when the specified encoding is 'hex' and the buffer has an odd length
(because a _string_ with an odd length is never a valid hex string.)

The sign/verify update() methods work okay because they use different
validation logic.

Fixes: https://github.com/nodejs/node/issues/31751

PR-URL: https://github.com/nodejs/node/pull/31766


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>