udp: add drop count for packets in udp_prod_queue

udp: add drop count for packets in udp_prod_queue

This commit adds SNMP drop count increment for the packets in
per NUMA queues which were introduced in commit b650bf0977d3
("udp: remove busylock and add per NUMA queues"). note that SNMP
counters are incremented currently by the caller for skb. And
that these skbs on the intermediate queue cannot be counted
there so need similar logic in their error path.

Signed-off-by: Mahdi Faramarzpour <mahdifrmx@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260129083806.204752-1-mahdifrmx@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>