net/mlx5e: Separate between netdev objects and mlx5e profiles initialization

1) Initialize netdevice features and structures on netdevice allocation
   and outside of the mlx5e profile.

2) As now mlx5e netdevice private params will be setup on profile init only
   after netdevice features are already set, we add  a call to
   netde_update_features() to resolve any conflict.
   This is nice since we reuse the fix_features ndo code if a profile
   wants different default features, instead of duplicating features
   conflict resolution code on profile initialization.

3) With this we achieve total separation between mlx5e profiles and
   netdevices, and will allow replacing mlx5e profiles on the fly to reuse
   the same netdevice for multiple profiles.
   e.g. for uplink representor profile as shown in the following patch

4) Profile callbacks are not allowed to touch netdev->features directly
   anymore, since in downstream patch we will detach/attach netdev
   dynamically to profile, hence we move the code dealing with
   netdev->features from profile->init() to fix_features ndo, and we
   will call netdev_update_features() on
   mlx5e_attach_netdev(profile, netdev);

Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>