Remove a redundant point mul from ossl_ec_key_public_check()

Remove a redundant point mul from ossl_ec_key_public_check()

This code was added in error and is entirely redundant. It is also an
expensive operation (e.g. see #21833).

Fixes #21834

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21902)

(cherry picked from commit 3961991593f788b3efb2a27563d358c7c58f854c)