net/mlx5e: Unify the RX flow

Generally an RX packet flows through the following objects:
Flow table --> TIR --> RQT --> RQ

Where:
- TIR stands for "Transport Interface Receive", defining the RSS and
  LRO paramaters.
- RQT stands for "RQ Table", implementing the RSS indirection table.
- RQ stands for "Receive Queue"

For flows that do not need LRO, nor RSS, the driver made a shortcut to
the above RX flow by pointing to the RQ directly from the TIR, yielding
this flow:
Flow table --> TIR --> RQ

In this commit we remove this shortcut by "inserting" a single-RQ RQT
between the TIR and the RQ, i.e RX packets will reach the same RQ but
will go through an RQT of size 1, pointing to just a single RQ.

This way the RX traffic re-direction to/from the "Drop RQ" will be more
uniform (AKA "one flow"), as it will involve only RQTs re-direction and
no TIRs re-direction.

Signed-off-by: Achiad Shochat <achiad@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>