net/mlx5: E-Switch, handle devcom events only for ports on the same device

This is the same check as LAG mode checks if to enable lag.
This will fix adding peer miss rules if lag is not supported
and even an incorrect rules in socket direct mode.

Also fix the incorrect comment on mlx5_get_next_phys_dev() as flow #1
doesn't exists.

Fixes: ac004b83

 ("net/mlx5e: E-Switch, Add peer miss rules")
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>