Add support for Intel 82574L to nicintel_spi.c.

Signed-off-by: Bill Paul <wpaul@windriver.com>
Acked-by: Idwer Vollering <vidwer@gmail.com>

git-svn-id: svn://flashrom.org/flashrom/trunk@1767 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1