demos/certs: properly handle "$@"

demos/certs: properly handle "$@"

There is little reason $@ should be used unquoted;  also, "$@"
should be used instead of $* in order to pass the script arguments
to a function.

Fixes: bcd92754d56a "demos: fix cert scripts"
Fixes: 79b184fb4b65 "Extend certificate creation examples to include CRL generation and sample"
Signed-off-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/28407)