.travis.yml: enable coverity again
.travis.yml: enable coverity again

The previous problems seem to be resolved, so enable it again.

This reverts commit 857b9db43c32cd5e8eef57d7140643c85ab56f8b.

Signed-off-by: Jan Luebbe <3a82f1ac4ad59607a20f180f1c67ac8ba31ad0d5@pengutronix.de>

rauc/rauc,ejoerns/rauc,ejoerns/rauc,rauc/rauc,ejoerns/rauc,jluebbe/rauc,jluebbe/rauc,jluebbe/rauc,rauc/rauc