net/nfp: fix reporting of RSS capabilities

net/nfp: fix reporting of RSS capabilities

Before this change the dev_infos callback always reported RSS
capabilities regardless of whether the capability is supported by the
device or not. First check the capabilities field in the BAR of the
device and advertise RSS functionality accordingly.

Fixes: 8b945a7f7dcb ("drivers/net: update Rx RSS hash offload capabilities")
Cc: stable@dpdk.org
Signed-off-by: Heinrich Kuhn <heinrich.kuhn@netronome.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>