[bug report] bcachefs: convert clock.c to CLASS/guards

Hello Kent Overstreet,

Commit 7ede8fc514bb ("bcachefs: convert clock.c to CLASS/guards")
from Jul 14, 2025 (linux-next), leads to the following Smatch static
checker warning:

	fs/bcachefs/clock.c:24 bch2_io_timer_add()
	warn: double unlock '&clock->timer_lock' (orig line 27)

fs/bcachefs/clock.c
    22 void bch2_io_timer_add(struct io_clock *clock, struct io_timer *timer)
    23 {
--> 24         guard(spinlock)(&clock->timer_lock);
                                ^^^^^^^^^^^^^^^^^
    25 
    26         if (time_after_eq64((u64) atomic64_read(&clock->now), timer->expire)) {
    27                 spin_unlock(&clock->timer_lock);
                                    ^^^^^^^^^^^^^^^^^

This spin_unlock() was accidentally left over when we converted to guard
locks.  It leads to a double unlock.

    28                 timer->fn(timer);
    29                 return;
    30         }
    31 
    32         for (size_t i = 0; i < clock->timers.nr; i++)
    33                 if (clock->timers.data[i] == timer)
    34                         return;
    35 
    36         BUG_ON(!min_heap_push(&clock->timers, &timer, &callbacks, NULL));
    37 }

regards,
dan carpenter