Btrfs: cleanup unused arguments of btrfs_csum_data

Argument 'root' is no more used in btrfs_csum_data().

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 1d80afa..6be083b 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -431,7 +431,7 @@
 	if (index == 0)
 		offset = sizeof(u32) * io_ctl->num_pages;
 
-	crc = btrfs_csum_data(io_ctl->root, io_ctl->orig + offset, crc,
+	crc = btrfs_csum_data(io_ctl->orig + offset, crc,
 			      PAGE_CACHE_SIZE - offset);
 	btrfs_csum_final(crc, (char *)&crc);
 	io_ctl_unmap_page(io_ctl);
@@ -461,7 +461,7 @@
 	kunmap(io_ctl->pages[0]);
 
 	io_ctl_map_page(io_ctl, 0);
-	crc = btrfs_csum_data(io_ctl->root, io_ctl->orig + offset, crc,
+	crc = btrfs_csum_data(io_ctl->orig + offset, crc,
 			      PAGE_CACHE_SIZE - offset);
 	btrfs_csum_final(crc, (char *)&crc);
 	if (val != crc) {