net/mlx5e: E-Switch, Register devcom device with switch id key

Register devcom devices with switch id instead of guid.
Devcom interface is used to sync between ports in the eswitch,
e.g. Adding miss rules between the ports.
New eswitch devices could have the same guid but a different
switch id so its more correct to group according to switch id
which is the identifier if the ports are on the same eswitch.

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