gve: process XSK TX descriptors as part of RX NAPI

gve: process XSK TX descriptors as part of RX NAPI

When busy polling is enabled, xsk_sendmsg for AF_XDP zero copy marks
the NAPI ID corresponding to the memory pool allocated for the socket.
In GVE, this NAPI ID will never correspond to a NAPI ID of one of the
dedicated XDP TX queues registered with the umem because XDP TX is not
set up to share a NAPI with a corresponding RX queue.

This patch moves XSK TX descriptor processing from the TX NAPI to the RX
NAPI, and the gve_xsk_wakeup callback is updated to use the RX NAPI
instead of the TX NAPI, accordingly. The branch on if the wakeup is for
TX is removed, as the NAPI poll should be invoked whether the wakeup is
for TX or for RX.

Fixes: fd8e40321a12 ("gve: Add AF_XDP zero-copy support for GQI-QPL format")
Cc: stable@vger.kernel.org
Signed-off-by: Praveen Kaligineedi <pkaligineedi@google.com>
Signed-off-by: Joshua Washington <joshwash@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>