e1000 linkage fix

ia64:

 drivers/built-in.o(.text+0xd9a72): In function `e1000_xmit_frame':
 : undefined reference to `csum_ipv6_magic'

Cc: Auke Kok <auke-jan.h.kok@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>