iwlwifi: Fix built-in compilation of iwlcore (part 2)

On Wed, 2008-04-23 at 13:38 +0300, Tomas Winkler wrote:
> This patch fixes problem in Makefile that prevented
> built-in compilation of iwlcore

Here is the second part. Without this,
drivers/net/wireless/iwlwifi/build-in.o will not be linked into vmlinux.

Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>