sb_edac: add support for Ivy Bridge

Since Ivy Bridge memory controller is very similar to Sandy Bridge, it's
wiser to modify sb_edac to support both instead of creating another
driver.

[m.chehab@samsung.com: Fix CodingStyle]
Signed-off-by: Aristeu Rozanski <arozansk@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>