EDAC/{skx_common,i10nm}: Fix incorrect far-memory error source indicator

The Granite Rapids CPUs with Flat2LM memory configurations may
mistakenly report near-memory errors as far-memory errors, resulting
in the invalid decoded ADXL results:

  EDAC skx: Bad imc -1

Fix this incorrect far-memory error source indicator by prefetching the
decoded far-memory controller ID, and adjust the error source indicator
to near-memory if the far-memory controller ID is invalid.

Fixes: ba987eaa ("EDAC/i10nm: Add Intel Granite Rapids server support")
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Tested-by: Diego Garcia Rodriguez <diego.garcia.rodriguez@intel.com>
Link: https://lore.kernel.org/r/20241015072236.24543-3-qiuxu.zhuo@intel.com