openssl req: don't try to report bits

With the introduction of -pkeyopt, the number of bits may change
without |newkey| being updated.  Unfortunately, there is no API to
retrieve the information from a EVP_PKEY_CTX either, so chances are
that we report incorrect information.  For the moment, it's better not
to try to report the number of bits at all.

Fixes #7086

Reviewed-by: Paul Yang <yang.yang@baishancloud.com>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7096)