netdevsim: Mark NAPI ID on skb in nsim_rcv

Previously, nsim_rcv was not marking the NAPI ID on the skb, leading to
applications seeing a napi ID of 0 when using SO_INCOMING_NAPI_ID.

To add to the userland confusion, netlink appears to correctly report
the NAPI IDs for netdevsim queues but the resulting file descriptor from
a call to accept() was reporting a NAPI ID of 0.

Signed-off-by: Joe Damato <jdamato@fastly.com>
Link: https://patch.msgid.link/20250424002746.16891-2-jdamato@fastly.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>