btrfs: make clear_extent_buffer_uptodate return void

Does not return any errors, nor anything from the callgraph.

Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 47db906..d5778e8 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5227,7 +5227,7 @@
 	return was_dirty;
 }
 
-int clear_extent_buffer_uptodate(struct extent_buffer *eb)
+void clear_extent_buffer_uptodate(struct extent_buffer *eb)
 {
 	unsigned long i;
 	struct page *page;
@@ -5240,7 +5240,6 @@
 		if (page)
 			ClearPageUptodate(page);
 	}
-	return 0;
 }
 
 void set_extent_buffer_uptodate(struct extent_buffer *eb)