net/mlx5e: Use static constant netdevice ndos

Currently our netdevice ops is a one static global variable which
is referenced by all mlx5e netdevice instances. This can be
problematic when different driver instances do not share same
HW capabilities (e.g SRIOV PF and VFs probed to the host).

Now we have two constant global netdevice ops variables, one
for basic netdevice ops and the other with extended SRIOV ops,
on netdevice construction we choose the one suitable for
current device capabilities.

Fixes: 66e49ded ("net/mlx5e: Add support for SR-IOV ndos")
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>