ethdev: fix RSS flow expansion in case of mismatch

ethdev: fix RSS flow expansion in case of mismatch

Function rte_flow_expand_rss() is used to expand a flow rule with
partial pattern into several rules, to ensure all relevant packets
are matched.
It uses utility function rte_flow_expand_rss_item_complete(), to check
if the last valid item in the flow rule pattern needs to be completed.
For example the pattern "eth / ipv4 proto is 17 / end" will be completed
with a "udp" item.
This function returns "void" item in two cases:
1) The last item has empty spec, for example "eth / ipv4 / end".
2) The last itme has spec that can't be expanded for RSS.
   For example the pattern "eth / ipv4 proto is 47 / end" ends with IPv4
   item that has next protocol GRE.

In both cases the flow rule may be expanded, but in the second case such
expansion may create rules with invalid pattern.
For example "eth / ipv4 proto is 47 / udp / end".
In such a case the flow rule should not be expanded.

This patch updates function rte_flow_expand_rss_item_complete().
Return value RTE_FLOW_ITEM_TYPE_END is used to indicate the flow rule
should not be expanded.
In such a case, rte_flow_expand_rss() will return with the original flow
rule only, without any expansion.

Fixes: fc2dd8dd492f ("ethdev: fix expand RSS flows")
Cc: stable@dpdk.org
Signed-off-by: Dekel Peled <dekelp@nvidia.com>
Acked-by: Xiaoyu Min <jackmin@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
Acked-by: Ori Kam <orika@nvidia.com>