mlxsw: spectrum: Replace vPorts with Port-VLAN

As explained in the cover letter, since the introduction of the bridge
offload in the mlxsw driver, information related to the offloaded bridge
and bridge ports was stored in the individual port struct,
mlxsw_sp_port.

This lead to a bloated struct storing both physical properties of the
port (e.g., autoneg status) as well as logical properties of an upper
bridge port (e.g., learning, mrouter indication). While this might work
well for simple devices, it proved to be hard to extend when stacked
devices were taken into account and more advanced use-cases (e.g., IGMP
snooping) considered.

This patch removes the excess information from the above struct and
instead stores it in more appropriate structs that represent the bridge
port, the bridge itself and a VLAN configured on the bridge port.

The membership of a port in a bridge is denoted using the Port-VLAN
struct, which points to the bridge port and also member in the bridge
VLAN group of the VLAN it represents. This allows us to completely
remove the vPort abstraction and consolidate many of the code paths
relating to VLAN-aware and unaware bridges.

Note that the FID / vFID code is currently duplicated, but this will
soon go away when the common FID core will be introduced.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>