datapath: Convert internal_dev to ndo_fix_features.

datapath: Convert internal_dev to ndo_fix_features.

From 2.6.39 kernel netdev features are set using set_features and
fix_features APIs. Since internal-dev does not need any special
checks on setting feature, there is no need to define set_features
or fix_features. Only hw_features needs to be set to features that
are supported by internal-dev.

Following patch does same and drops discrete offload setting ops for
newer kernel.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>
Bug #7772