Fix potential SCA vulnerability in some EC_METHODs

Fix potential SCA vulnerability in some EC_METHODs

This commit addresses a potential side-channel vulnerability in the
internals of some elliptic curve low level operations.
The side-channel leakage appears to be tiny, so the severity of this
issue is rather low.

The issue was reported by David Schrammel and Samuel Weiser.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/9239)

(cherry picked from commit 3cb914c463ed1c9e32cfb773d816139a61b6ad5f)