e1000: fix sw fw sync on igb i210/i211

I finally had a look at the datasheet and spotted an additional
register address difference between regular E1000 and i210/i211 chips.
This patch fixes this and now successfully works on programmed
i210/i211 as well as unprogrammed i211.

Signed-off-by: Marcel Ziswiler <marcel@ziswiler.com>