enhance ethtool error message
enhance ethtool error message

Change-Id: Ib28b976ac6e9182f8f2fce16a27e5333c73c0e42
Reviewed-on: https://softwarefactory-project.io/r/5352
Reviewed-by: Sylvain Baubeau <b0a7dc08a3f38d713e107103b0a85b0badc14b84@redhat.com>
Reviewed-by: Sylvain Afchain <b9baee1c2e4cc202620c6529e0c0bd3dbc38b6dc@gmail.com>
Tested-by: Sylvain Baubeau <b0a7dc08a3f38d713e107103b0a85b0badc14b84@redhat.com>
Workflow: Sylvain Baubeau <b0a7dc08a3f38d713e107103b0a85b0badc14b84@redhat.com>

skydive-project/skydive,safchain/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,lebauce/skydive,redhat-cip/skydive,lebauce/skydive,redhat-cip/skydive,safchain/skydive,lebauce/skydive,safchain/skydive,safchain/skydive,lebauce/skydive,redhat-cip/skydive,safchain/skydive,lebauce/skydive,lebauce/skydive,safchain/skydive,skydive-project/skydive,skydive-project/skydive,skydive-project/skydive,safchain/skydive,safchain/skydive,skydive-project/skydive,lebauce/skydive