net/mlx5e: Set drop RQ's necessary parameters only

By its role, there is no need to set all the other parameters
for the drop RQ.

Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>