net/mlx4_core: Protect QUERY_PORT wrapper from untrusted guests

The function mlx4_QUERY_PORT_wrapper implements only the
QUERY_PORT "general" case (opcode modifier = 0).

Verify that the opcode modifier is zero, and also that the
input modifier contains only the port number in bits 0..7
(all other bits should be zero).

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>