Coverity points out that if 'dom' isn't returned from virDomainQemuAttach,
then the code already jumps to cleanup, so there was no need for the
subsequent if (dom != NULL) check.
I moved the error message about failure into the goto cleanup on failure
and then removed the if (dom != NULL)
Signed-off-by: John Ferlan <jferlan@redhat.com>