dm log-writes: Add missing set_freezable() for freezable kthread

The log_writes_kthread() calls try_to_freeze() but lacks set_freezable(),
rendering the freeze attempt ineffective since kernel threads are
non-freezable by default. This prevents proper thread suspension during
system suspend/hibernate.

Add set_freezable() to explicitly mark the thread as freezable.

Fixes: 0e9cebe72459 ("dm: add log writes target")
Signed-off-by: Haotian Zhang <[e-mail]>
Reviewed-by: Benjamin Marzinski <[e-mail]>
Signed-off-by: Mikulas Patocka <[e-mail]>

drivers/md/dm-log-writes.c

···
 	struct log_writes_c *lc = arg;
 	sector_t sector = 0;
 
+	set_freezable();
 	while (!kthread_should_stop()) {
 		bool super = false;
 		bool logging_enabled;