pciauto_setup_device bars_num fix

Passing bars_num=0 to pciauto_setup_device should assign no bars.

Signed-off-by: Ed Swarthout <Ed.Swarthout@freescale.com>
Acked-by: Shinya Kuribayashi <shinya.kuribayashi@necel.com>
Acked-by: Andy Fleming <afleming@freescale.com>