devicemapper: mention dm.directlvm_device in its error message
devicemapper: mention dm.directlvm_device in its error message

Mention the dm.directlvm_device option in the error message that we
return when it isn't set.

Signed-off-by: Nalin Dahyabhai <f562fcb2a0b898bf0be1afc867ea92325d8f825f@redhat.com>

rhatdan/storage,rhatdan/storage,containers/storage,containers/storage,rhatdan/storage,containers/storage