Btrfs: use <= instead of < in is_extent_unchanged

Used the wrong compare operator here.
Reported-by: NAlex Lyakas <alex.bolshoy.btrfs@gmail.com>
Signed-off-by: NAlexander Block <ablock84@googlemail.com>

fs/btrfs/send.c

@@ -3802,7 +3802,7 @@ static int is_extent_unchanged(struct send_ctx *sctx,
 		 * Are we at extent 8? If yes, we know the extent is changed.
 		 * This may only happen on the first iteration.
 		 */
-		if (found_key.offset + right_len < ekey->offset) {
+		if (found_key.offset + right_len <= ekey->offset) {
 			ret = 0;
 			goto out;
 		}