net/sfc: add simple port representor statistics
net/sfc: add simple port representor statistics

Gather statistics of enqueued and dequeued packets in Rx and Tx burst
callbacks to report in stats_get callback.

Signed-off-by: Igor Romanov <945ea196dab32ad63762a1b623439a95515e898a@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <4155e7bf8e0185127625dac6d84336299844982f@oktetlabs.ru>
Reviewed-by: Andy Moreton <adbee5d9b6a6a553b71b14302d03837591e26c9d@xilinx.com>
Reviewed-by: Ivan Malov <436a2feb05eb79a6862681e66bd0193220e8fb2d@oktetlabs.ru>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk