Calls to DIOCSYNCSLICEINFO were being made with the assumption that
CD_FLAG_OPEN indicated an already-open device. With recent changes this
flag is set prior to the check and the calls were being made without
any slice information, causing a panic. For now follow what FreeBSD did
and just remove the calls.
Remove redundant setting of CD_FLAG_OPEN.
Reported-by: VOROSKOI Andras <sinknull@crater.dragonflybsd.org>,
Michael Neumann <mneumann@ntecs.de>
Dragonfly-bug: <http://bugs.dragonflybsd.org/issue1016>