as with disk devices, don't fail when some unix devices fail to be deleted
as with disk devices, don't fail when some unix devices fail to be deleted

Signed-off-by: Tycho Andersen <10c18fcb898ee6b17d6575d444b125d10b3f4d6a@canonical.com>

akshaykarle/lxd,jsavikko/lxd,hallyn/lxd,stgraber/lxd,techtonik/lxd,techtonik/lxd,lxc/lxd,mjeanson/lxd,chrisglass/lxd,erikmack/lxd,hallyn/lxd,techtonik/lxd,mjeanson/lxd,erikmack/lxd,stgraber/lxd,akshaykarle/lxd,Skarlso/lxd,pcdummy/lxd,atxwebs/lxd,jsavikko/lxd,lxc/lxd,jsavikko/lxd,stgraber/lxd,stgraber/lxd,georghopp/lxd,atxwebs/lxd,Skarlso/lxd,atxwebs/lxd,pcdummy/lxd,lxc/lxd,akshaykarle/lxd,mjeanson/lxd,ollie314/lxd,chrisglass/lxd,ollie314/lxd,lxc/lxd,lxc/lxd,georghopp/lxd,hallyn/lxd,stgraber/lxd,hallyn/lxd,stgraber/lxd,ollie314/lxd,lxc/lxd,lxc/lxd,georghopp/lxd,hallyn/lxd,erikmack/lxd,pcdummy/lxd,atxwebs/lxd,chrisglass/lxd,Skarlso/lxd,Skarlso/lxd,hallyn/lxd,stgraber/lxd