sb_edac: support for Broadwell -EP and -EX

Basic support for the single socket Broadwell-DE processor
was added back in commit 1f39581a
   sb_edac: Add support for Broadwell-DE processor
This patch extends Broadwell support to cover the two
socket "-EP" and four socket "-EX" versions of Broadwell.
Only tested on the 2 socket - but this code is largely
cloned from the Haswell path.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>