net: Move void devices dumping in a separate helper
net: Move void devices dumping in a separate helper

To make it look symmetrical to over types dumping.
And for simpler further patching.

Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@parallels.com>

marcosnils/criu,kawamuray/criu,wtf42/criu,KKoukiou/criu-remote,svloyso/criu,rentzsch/criu,marcosnils/criu,eabatalov/criu,eabatalov/criu,sdgdsffdsfff/criu,LK4D4/criu,eabatalov/criu,biddyweb/criu,gonkulator/criu,LK4D4/criu,ldu4/criu,AuthenticEshkinKot/criu,gablg1/criu,marcosnils/criu,fbocharov/criu,tych0/criu,svloyso/criu,biddyweb/criu,gablg1/criu,wtf42/criu,eabatalov/criu,gablg1/criu,gonkulator/criu,efiop/criu,marcosnils/criu,kawamuray/criu,rentzsch/criu,biddyweb/criu,rentzsch/criu,efiop/criu,KKoukiou/criu-remote,AuthenticEshkinKot/criu,LK4D4/criu,fbocharov/criu,kawamuray/criu,efiop/criu,marcosnils/criu,sdgdsffdsfff/criu,ldu4/criu,sdgdsffdsfff/criu,LK4D4/criu,KKoukiou/criu-remote,tych0/criu,efiop/criu,gonkulator/criu,rentzsch/criu,wtf42/criu,svloyso/criu,tych0/criu,gonkulator/criu,ldu4/criu,gablg1/criu,AuthenticEshkinKot/criu,kawamuray/criu,sdgdsffdsfff/criu,svloyso/criu,marcosnils/criu,ldu4/criu,ldu4/criu,eabatalov/criu,svloyso/criu,KKoukiou/criu-remote,rentzsch/criu,AuthenticEshkinKot/criu,biddyweb/criu,KKoukiou/criu-remote,sdgdsffdsfff/criu,sdgdsffdsfff/criu,fbocharov/criu,fbocharov/criu,efiop/criu,svloyso/criu,LK4D4/criu,tych0/criu,wtf42/criu,gonkulator/criu,biddyweb/criu,biddyweb/criu,ldu4/criu,tych0/criu,tych0/criu,KKoukiou/criu-remote,kawamuray/criu,gablg1/criu,wtf42/criu,wtf42/criu,kawamuray/criu,gablg1/criu,eabatalov/criu,gonkulator/criu,fbocharov/criu,AuthenticEshkinKot/criu,AuthenticEshkinKot/criu,fbocharov/criu,LK4D4/criu,efiop/criu,rentzsch/criu