net/mlx5: fix pop VLAN action validation

net/mlx5: fix pop VLAN action validation

Validation function of 'POP VLAN' action includes check for other
'POP VLAN' actions present in flow.
It doesn't check for 'PUSH VLAN' actions present in flow.

This patch adds check for 'PUSH VLAN' actions present in flow.

Fixes: b41e47da2592 ("net/mlx5: support pop flow action on VLAN header")
Cc: stable@dpdk.org
Signed-off-by: Dekel Peled <dekelp@mellanox.com>
Acked-by: Ori Kam <orika@mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>