net/i40e: optimize flow director update rate

net/i40e: optimize flow director update rate

This patch optimized the fdir update rate for i40e PF, by tracking
whether the fdir rule being inserted into the guaranteed space
or shared space.
For the flows that are inserted to the guaranteed space, we assume
that the insertion will always succeed as the hardware only report
the "no enough space left" error. In this case, the software can
directly return success and no need to retrieve the result from
the hardware. When destroying a flow, we also assume the operation
will succeed as the software has checked the flow is indeed in
the hardware.
See the fdir programming status descriptor format in the datasheet
for more details.

Signed-off-by: Chenmin Sun <chenmin.sun@intel.com>
Reviewed-by: Jingjing Wu <jingjing.wu@intel.com>