net/mlx5e: Add support for multiple profiles

To allow support in representor netdevices where we create more than one
netdevice per NIC, add profiles to the mlx5e driver. The profiling
allows for creation of mlx5e instances with different characteristics.

Each profile implements its own behavior using set of function pointers
defined in struct mlx5e_profile. This is done to allow for avoiding complex
per profix branching in the code.

Currently only the profile for the conventional NIC is implemented,
which is of use when a netdev is created upon pci probe.

This patch doesn't add any new functionality.

Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>