gve: add XDP_TX and XDP_REDIRECT support for DQ RDA

This patch adds support for XDP_TX and XDP_REDIRECT for the DQ RDA
queue format. To appropriately support transmission of XDP frames, a
new pending packet type GVE_TX_PENDING_PACKET_DQO_XDP_FRAME is
introduced for completion handling, as there was a previous assumption
that completed packets would be SKBs.

XDP_TX handling completes the basic XDP actions, so the feature is
recorded accordingly. This patch also enables the ndo_xdp_xmit callback
allowing DQ to handle XDP_REDIRECT packets originating from another
interface.

The XDP spinlock is moved to common TX ring fields so that it can be
used in both GQ and DQ. Originally, it was in a section which was
mutually exclusive for GQ and DQ.

In summary, 3 XDP features are exposed for the DQ RDA queue format:
1) NETDEV_XDP_ACT_BASIC
2) NETDEV_XDP_ACT_NDO_XMIT
3) NETDEV_XDP_ACT_REDIRECT

Note that XDP and header-data split are mutually exclusive for the time
being due to lack of multi-buffer XDP support.

This patch does not add support for the DQ QPL format. That is to come
in a future patch series.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Praveen Kaligineedi <pkaligineedi@google.com>
Signed-off-by: Joshua Washington <joshwash@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>