Btrfs: Fix 32 bit compiles by using an unsigned long byte count in the ordered extent

The ordered extents have to fit in memory, so an unsigned long is sufficient.
Signed-off-by: NChris Mason <chris.mason@oracle.com>

fs/btrfs/ordered-data.h

@@ -95,7 +95,8 @@ struct btrfs_ordered_extent {
  * calculates the total size you need to allocate for an ordered sum
  * structure spanning 'bytes' in the file
  */
-static inline int btrfs_ordered_sum_size(struct btrfs_root *root, u64 bytes)
+static inline int btrfs_ordered_sum_size(struct btrfs_root *root,
+					 unsigned long bytes)
 {
 	unsigned long num_sectors = (bytes + root->sectorsize - 1) /
 		root->sectorsize;