Btrfs: remove unused code in split_state()

These two lines are not used, remove them.

Signed-off-by: Qinghuang Feng <qhfeng.kernel@gmail.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 37d43b5..ebe6b29 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -415,8 +415,6 @@
 
 	node = tree_insert(&tree->state, prealloc->end, &prealloc->rb_node);
 	if (node) {
-		struct extent_state *found;
-		found = rb_entry(node, struct extent_state, rb_node);
 		free_extent_state(prealloc);
 		return -EEXIST;
 	}