Remove --ncp-disable option

Remove --ncp-disable option

NCP has proven to be stable and apart from the one VPN Provider doing
hacky things with homebrewed NCP we have not had any reports about
ncp-disable being required. Remove ncp-disable to simplify code paths.

Note: This patch breaks client without --pull. The follow up patch
for P2P NCP will restore that. But to avoid all the NCP/non-NCP special
cases to be implemented in P2P. P2P will directly switch from always
non-NCP to always NCP.

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Antonio Quartulli <antonio@openvpn.net>
Message-Id: <20210520151148.2565578-8-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg22418.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>