EDAC, skx_edac: Fix detection of single-rank DIMMs

Single-rank DIMMs did not get detected on Skylake/Kabylake systems due
to wrong limit check. The single rank DIMM check is a simple typo. "0"
is a legal value in this field meaning single rank.

Signed-off-by: Charles Rose <charles.rose@dell.com>
Cc: Aristeu Rozanski <arozansk@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/66df72d327c265fbf92fe25df96daa228a35f076.1506358467.git.tony.luck@intel.com


[ Also fix debug message to print number of ranks. ]
Signed-off-by: Tony Luck <tony.luck@intel.com>
[ Expand commit message. ]
Signed-off-by: Borislav Petkov <bp@suse.de>