net/cxgbe: parse and validate flows

net/cxgbe: parse and validate flows

Introduce rte_flow skeleton and implement validate operation.

Parse and convert <item>, <action>, <attributes> into hardware
specification. Perform validation, including basic sanity tests
and underlying device's supported filter capability checks.

Currently add support for:
<item>: IPv4, IPv6, TCP, and UDP.
<action>: Drop, Queue, and Count.

Also add sanity checks to ensure filters are created at specified
index in LE-TCAM region. The index in LE-TCAM region indicates
the filter rule's priority with index 0 having the highest priority.
If no index is specified, filters are created at closest available
free index.

Signed-off-by: Shagun Agrawal <shaguna@chelsio.com>
Signed-off-by: Kumar Sanghvi <kumaras@chelsio.com>
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>