Btrfs: remove non-sense btrfs_error_discard_extent() function

It doesn't do anything special, it just calls btrfs_discard_extent(),
so just remove it.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 4f3c03d..a80b971 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1889,8 +1889,8 @@
 	return blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_NOFS, 0);
 }
 
-static int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr,
-				u64 num_bytes, u64 *actual_bytes)
+int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr,
+			 u64 num_bytes, u64 *actual_bytes)
 {
 	int ret;
 	u64 discarded_bytes = 0;
@@ -9698,12 +9698,6 @@
 	return unpin_extent_range(root, start, end, false);
 }
 
-int btrfs_error_discard_extent(struct btrfs_root *root, u64 bytenr,
-			       u64 num_bytes, u64 *actual_bytes)
-{
-	return btrfs_discard_extent(root, bytenr, num_bytes, actual_bytes);
-}
-
 int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;