EDAC, sb_edac: Fix reporting for patrol scrubber errors

sb_edac sometimes reports the wrong DIMM for a memory error found by
the patrol scrubber. That is because the hardware provides only a 4KB
page-aligned address for the error case.

This means that the EDAC driver will point at the DIMM matching offset
0x0 in the 4KB page, but because of interleaving across channels and
ranks, the actual DIMM involved may be different if the error is on some
other cache line within the page.

Therefore, reconstruct the socket/iMC/channel information from the "mce"
structure passed to the EDAC driver. The DIMM cannot be determined, so
pass "dimm=-1" to the EDAC core. It will report that all the DIMMs on
that channel may be affected.

Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/20180907230828.13901-3-tony.luck@intel.com


[ Improve comments on the functions to convert bank number
  to memory controller number. Minor cleanup to commit message. ]
Signed-off-by: Tony Luck <tony.luck@intel.com>
[ Massage commit message more. ]
Signed-off-by: Borislav Petkov <bp@suse.de>