mini2440: fix nand boot first 4KB issue

commit 417a3c04b64a02d1028decfea7f05d706c6bc983 fix link libmini2440
first by changing Makefile at root directory, it's not a good idea to do
that, we could do this better this time.

Signed-off-by: Fudong Bai <fudongbai@gmail.com>