e1000: add ich8lan core functions

This implements the core new functions needed for ich8's internal
NIC. This includes:

* ich8 specific read/write code
* flash/nvm access code
* software semaphore flag functions
* 10/100 PHY (fe - no gigabit speed) support for low-end versions
* A workaround for a powerdown sequence problem discovered that
affects a small number of motherboard.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>