Btrfs: remove unused hint byte argument for btrfs_drop_extents

I audited all users of btrfs_drop_extents and found that nobody actually uses
the hint_byte argument.  I'm sure it was used for something at some point but
it's not used now, and the way the pinning works the disk bytenr would never be
immediately useful anyway so lets just remove it.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 24745b8..f0a4792 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -230,7 +230,6 @@
 	u64 inline_len = actual_end - start;
 	u64 aligned_end = (end + root->sectorsize - 1) &
 			~((u64)root->sectorsize - 1);
-	u64 hint_byte;
 	u64 data_len = inline_len;
 	int ret;
 
@@ -247,8 +246,7 @@
 		return 1;
 	}
 
-	ret = btrfs_drop_extents(trans, root, inode, start, aligned_end,
-				 &hint_byte, 1);
+	ret = btrfs_drop_extents(trans, root, inode, start, aligned_end, 1);
 	if (ret)
 		return ret;
 
@@ -1786,7 +1784,6 @@
 	struct btrfs_path *path;
 	struct extent_buffer *leaf;
 	struct btrfs_key ins;
-	u64 hint;
 	int ret;
 
 	path = btrfs_alloc_path();
@@ -1805,8 +1802,7 @@
 	 * with the others.
 	 */
 	ret = btrfs_drop_extents(trans, root, inode, file_pos,
-				 file_pos + num_bytes,
-				 &hint, 0);
+				 file_pos + num_bytes, 0);
 	if (ret)
 		goto out;
 
@@ -3629,7 +3625,6 @@
 		last_byte = (last_byte + mask) & ~mask;
 		if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
 			struct extent_map *hole_em;
-			u64 hint_byte = 0;
 			hole_size = last_byte - cur_offset;
 
 			trans = btrfs_start_transaction(root, 3);
@@ -3640,8 +3635,7 @@
 
 			err = btrfs_drop_extents(trans, root, inode,
 						 cur_offset,
-						 cur_offset + hole_size,
-						 &hint_byte, 1);
+						 cur_offset + hole_size, 1);
 			if (err) {
 				btrfs_abort_transaction(trans, root, err);
 				btrfs_end_transaction(trans, root);