Fix vrouter compilation issues for >3.15 kernels

* SET_ETHTOOL_OPS macro is removed in 3.16 kernels
* rxhash of sk_buff has been renamed to hash in 3.15 kernels.

This patch fixes this issue.

Change-Id: Ic0de873d0a5d869624ad9d5b883586222e8119cc
Closes-bug: #1383647
Merge "Fix vrouter compilation issues for >3.15 kernels"