net/mlx5e: Update check for merged eswitch device

The current check only validates if both netdevs use the same ops
which means both are vf reps or both uplink reps.

Unlike the case where the two uplinks are bonded (VF LAG), under
multipath scheme the switchdev parent id is not unified between the
uplink reps (and all the associated vf reps). However, we still want
to duplicate in the driver encap flows, adjust the merged eswitch
check for that matter.

Signed-off-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>