bgpd: fix crash when as/type mismatches in config

bgpd: fix crash when as/type mismatches in config

When we're trying to create the config for already existing router and
the AS number or instance type mismatches, we're returning the
inconsistency error and don't set the NB entry.

Any subsequent command that configures this router will crash because
every command relies on the existence of the NB entry.

Let's store the entry even when there's a mismatch to prevent the crash.

Signed-off-by: Igor Ryzhov <iryzhov@nfware.com>