net/mlx5: E-Switch, Fix the warning on vport index out of range

When eswitch gets vport data structure, the index should not be out
of the range of the vport array. Driver mistakenly used vport number
to check the range.

Fixes: 22b8ddc86bf4 ("net/mlx5: E-Switch, Assign a different position for uplink rep and vport")
Signed-off-by: Bodong Wang <bodong@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>