net/bnxt: improve CPR handling in vector path

net/bnxt: improve CPR handling in vector path

Reduce overhead of CPR descriptor validity checking in vector
receive and transmit functions.

Preserve raw cpr consumer index in vector transmit completion
function.

Remove an unneeded prefetch (per benchmarking) from vector
transmit completion function.

Fixes: bc4a000f2f53 ("net/bnxt: implement SSE vector mode")
Cc: stable@dpdk.org
Signed-off-by: Lance Richardson <lance.richardson@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>