bcache: bch_allocator_thread() is not freezable

bch_allocator_thread() is calling try_to_freeze(), but that's just an
expensive no-op given the fact that the thread is not marked freezable.

Bucket allocator has to be up and running to the very last stages of the
suspend, as the bcache I/O that's in flight (think of writing an
hibernation image to a swap device served by bcache).
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
Signed-off-by: NJens Axboe <axboe@fb.com>

drivers/md/bcache/alloc.c

@@ -64,7 +64,6 @@
 #include "btree.h"
 
 #include <linux/blkdev.h>
-#include <linux/freezer.h>
 #include <linux/kthread.h>
 #include <linux/random.h>
 #include <trace/events/bcache.h>
@@ -288,7 +287,6 @@ do {									\
 		if (kthread_should_stop())				\
 			return 0;					\
 									\
-		try_to_freeze();					\
 		schedule();						\
 		mutex_lock(&(ca)->set->bucket_lock);			\
 	}								\