i7core_edac: Add an EDAC memory controller driver for Nehalem chipsets

This driver is meant to support i7 core/i7core extreme desktop
processors and Xeon 35xx/55xx series with integrated memory controller.
It is likely that it can be expanded in the future to work with other
processor series based at the same Memory Controller design.

For now, it has just a few MCH status reads.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>