ether_nh_input: no mbuf packet header!

[dsalychev]

I've stumbled upon this panic during a network load test:

# uname -apKU
FreeBSD guardian 14.0-ALPHA2 FreeBSD 14.0-ALPHA2 aarch64 1400096 #1 main-n264908-58983e4b0253: Sun Aug 20 12:31:18 CEST 2023     dsl@diskless.tower.home:/usr/obj/usr/src/arm64.aarch64/sys/GENERIC arm64 aarch64 1400096 1400096
...
panic: ether_nh_input: no mbuf packet header!
cpuid = 4
time = 14861
KDB: stack backtrace:
db_trace_self() at db_trace_self
db_trace_self_wrapper() at db_trace_self_wrapper+0x30
vpanic() at vpanic+0x19c
panic() at panic+0x44
ether_nh_input() at ether_nh_input+0x460
netisr_dispatch_src() at netisr_dispatch_src+0xe0
ether_input() at ether_input+0xa0
dpaa2_ni_rx() at dpaa2_ni_rx+0x1fc
dpaa2_ni_cleanup_task() at dpaa2_ni_cleanup_task+0x174
taskqueue_run_locked() at taskqueue_run_locked+0x17c
taskqueue_thread_loop() at taskqueue_thread_loop+0xc8
fork_exit() at fork_exit+0x74
fork_trampoline() at fork_trampoline+0x14
KDB: enter: panic
[ thread pid 0 tid 100134 ]
Stopped at      kdb_enter+0x44: str     xzr, [x19, #768]

I haven't ever seen it before.