EDAC, amd64_edac: Extend scrub rate support to F15hM60h

The scrub rate control register has moved to function 2 in PCI config
space and is at a different offset on family 0x15, models 0x60 and
later. The minimum recommended scrub rate has also changed. (Refer to
D18F2x1c9_dct[1:0][DramScrub] in Fam15hM60h BKDG).

Adjust set_scrub_rate() and get_scrub_rate() functions to accommodate
this.

Tested on F15hM60h, Fam15h, models 00h-0fh and Fam10h systems.

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/1443440593-2316-2-git-send-email-Aravind.Gopalakrishnan@amd.com
[ Cleanup conditionals. ]
Signed-off-by: Borislav Petkov <bp@suse.de>