Add ethtool support to the L23network module

backport to 4.1

Change-Id: I5c74b503b13847eac5176b7e0561fcc0a95e0822
Partial-bug: #1275650
Implements: blueprint ethtool-at-boot-by-l23network
Merge "Add ethtool support to the L23network module" into stable/4.1