mroute: Remove unused mask argument of mroute_get_in*

mroute: Remove unused mask argument of mroute_get_in*

These are obsolete since the removal of pf feature.
Avoids spurious conversion warnings.

Change-Id: I501bf780957a9c685eed5994a15de09c28efc3f0
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1309
Message-Id: <20251028122028.24628-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg33939.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>