Tweak the client side PSK callback
Tweak the client side PSK callback

Ensure that we properly distinguish between successful return (PSK
provided), successful return (no PSK provided) and failure.

Reviewed-by: Rich Salz <c04971a99e5a9ee80eaab4b1deb37e845b0bd697@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3670)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl