xkey: Use a custom error level for debug messages

xkey: Use a custom error level for debug messages

D_XKEY = loglev(6, 69, M_DEBUG) is defined and used for
all low level debug messages  from xkey_provider.c and
xkey_helper.c

As suggested by Arne Schwabe <arne@rfc2549.org>

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <20220125025128.2117-1-selva.nair@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg23649.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>