net/mlx5: fix next protocol RSS expansion

net/mlx5: fix next protocol RSS expansion

RSS expansion scheme has 2 operational modes: default and specific.
The default mode expands into all valid options for a given network
layer. For example, Ethernet expands by default into VLAN, IPv4 and
IPv6, L3 expands into TCP and UDP, etc.
The specific mode expands according to flow item next protocol
configuration provided by the item spec and mask parameters.
There are 3 outcomes for the specific expansion:
1. Back to default – that is the case when result of (spec & mask)
   allows all possibilities.
   For example: eth type mask 0 type spec 0
2. No results – in that case item configuration has no valid expansion.
   For example: eth type mask 0xffff type spec 101
3. Direct - In that case flow item mask and spec configuration return
   valid expansion  option.
   Example: eth type mask 0x0fff type spec 0x0800.

Current PMD expands flow items with explicit spec and mask
configuration into the Direct(3) or No results (2). Default expansions
were handled as No results.

Fixes: f3f1f576f438 ("net/mlx5: fix RSS expansion with explicit next protocol")
Cc: stable@dpdk.org
Signed-off-by: Gregory Etelson <getelson@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>