fs: btrfs: Fix wrong comparison in logical to physical mapping

The comparison
  logical > item->logical + item->length
in btrfs_map_logical_to_physical is wrong and should be instead
  logical >= item->logical + item->length
For example, if
  item->logical = 4096
  item->length = 4096
and we are looking for logical = 8192, it is not part of item (item is
[4096, 8191]). But the comparison is false and we think we have found
the correct item, although we should be searing in the right subtree.

This fixes some bugs I encountered.

Signed-off-by: Marek Behun <marek.behun@nic.cz>

fs/btrfs/chunk-map.c

@@ -78,7 +78,7 @@ u64 btrfs_map_logical_to_physical(u64 logical)
 
 		if (item->logical > logical)
 			node = node->rb_left;
-		else if (logical > item->logical + item->length)
+		else if (logical >= item->logical + item->length)
 			node = node->rb_right;
 		else
 			return item->physical + logical - item->logical;