igb: Link queues to NAPI instances

igb: Link queues to NAPI instances

Link queues to NAPI instances via netdev-genl API. This is required to use
XDP/ZC busy polling. See commit 5ef44b3cb43b ("xsk: Bring back busy polling
support") for details.

This also allows users to query the info with netlink:

|$ ./tools/net/ynl/pyynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
|                               --dump queue-get --json='{"ifindex": 2}'
|[{'id': 0, 'ifindex': 2, 'napi-id': 8201, 'type': 'rx'},
| {'id': 1, 'ifindex': 2, 'napi-id': 8202, 'type': 'rx'},
| {'id': 2, 'ifindex': 2, 'napi-id': 8203, 'type': 'rx'},
| {'id': 3, 'ifindex': 2, 'napi-id': 8204, 'type': 'rx'},
| {'id': 0, 'ifindex': 2, 'napi-id': 8201, 'type': 'tx'},
| {'id': 1, 'ifindex': 2, 'napi-id': 8202, 'type': 'tx'},
| {'id': 2, 'ifindex': 2, 'napi-id': 8203, 'type': 'tx'},
| {'id': 3, 'ifindex': 2, 'napi-id': 8204, 'type': 'tx'}]

Add rtnl locking to PCI error handlers, because netif_queue_set_napi()
requires the lock held.

While at __igb_open() use RCT coding style.

Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Joe Damato <jdamato@fastly.com>
Tested-by: Sweta Kumari <sweta.kumari@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>