dco_linux: rearrange functions

dco_linux: rearrange functions

In preparation for the implementation of a generic netlink
message parser, move all parsing functions above ovpn_handle_msg().

The latter is soon going to become a generic message parser which
will invoke specific handlers, thus they are required to be defined
earlier in the file.

No functional change is intended.

This patch is only meant to reduce entropy in the patch which will do
the real netlink parser change.

Better reviewed with: git show --color-moved

Change-Id: I94004579aef4a1ccccdbcf8edd7b722e5a611c72
Signed-off-by: Antonio Quartulli <antonio@mandelbit.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20250723060747.19524-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg32263.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>