net: hsr: remove WARN_ONCE() in send_hsr_supervision_frame()

commit 37e8c97e upstream.

Syzkaller reported [1] hitting a warning after failing to allocate
resources for skb in hsr_init_skb(). Since a WARN_ONCE() call will
not help much in this case, it might be prudent to switch to
netdev_warn_once(). At the very least it will suppress syzkaller
reports such as [1].

Just in case, use netdev_warn_once() in send_prp_supervision_frame()
for similar reasons.

[1]
HSR: Could not send supervision frame
WARNING: CPU: 1 PID: 85 at net/hsr/hsr_device.c:294 send_hsr_supervision_frame+0x60a/0x810 net/hsr/hsr_device.c:294
RIP: 0010:send_hsr_supervision_frame+0x60a/0x810 net/hsr/hsr_device.c:294
...
Call Trace:
 <IRQ>
 hsr_announce+0x114/0x370 net/hsr/hsr_device.c:382
 call_timer_fn+0x193/0x590 kernel/time/timer.c:1700
 expire_timers kernel/time/timer.c:1751 [inline]
 __run_timers+0x764/0xb20 kernel/time/timer.c:2022
 run_timer_softirq+0x58/0xd0 kernel/time/timer.c:2035
 __do_softirq+0x21a/0x8de kernel/softirq.c:553
 invoke_softirq kernel/softirq.c:427 [inline]
 __irq_exit_rcu kernel/softirq.c:632 [inline]
 irq_exit_rcu+0xb7/0x120 kernel/softirq.c:644
 sysvec_apic_timer_interrupt+0x95/0xb0 arch/x86/kernel/apic/apic.c:1076
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:649
...

This issue is also found in older kernels (at least up to 5.10).

Cc: stable@vger.kernel.org
Reported-by:  <syzbot+3ae0a3f42c84074b7c8e@syzkaller.appspotmail.com>
Fixes: 121c33b0 ("net: hsr: introduce common code for skb initialization")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>