btrfs: move math functions to misc.h

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -14,6 +14,7 @@
 #include <linux/semaphore.h>
 #include <linux/uuid.h>
 #include <linux/list_sort.h>
+#include "misc.h"
 #include "ctree.h"
 #include "extent_map.h"
 #include "disk-io.h"
@@ -24,7 +25,6 @@
 #include "async-thread.h"
 #include "check-integrity.h"
 #include "rcu-string.h"
-#include "math.h"
 #include "dev-replace.h"
 #include "sysfs.h"
 #include "tree-checker.h"