Burner: fix ImportExport
Burner: fix ImportExport

Update the call to CreateInstance used in ImportExport to the new API for
multidisk/nic.

Reviewed-by: iustinp


ganeti-github-testing/ganeti-test-1,apyrgio/ganeti,apyrgio/snf-ganeti,andir/ganeti,dimara/ganeti,yiannist/ganeti,ganeti/ganeti,leshchevds/ganeti,andir/ganeti,leshchevds/ganeti,mbakke/ganeti,grnet/snf-ganeti,andir/ganeti,dimara/ganeti,apyrgio/ganeti,ganeti-github-testing/ganeti-test-1,bitemyapp/ganeti,onponomarev/ganeti,grnet/snf-ganeti,mbakke/ganeti,leshchevds/ganeti,bitemyapp/ganeti,mbakke/ganeti,ganeti/ganeti,ganeti/ganeti,onponomarev/ganeti,yiannist/ganeti,apyrgio/snf-ganeti,yiannist/ganeti