Move MCA_ADDR[ErrorAddr] extraction into a separate helper function. This
will be further refactored to support extended ErrorAddr bits in MCA_ADDR
in newer AMD CPUs.

  [ bp: Massage. ]
Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>
Link: https://lore.kernel.org/all/20220225193342.215780-3-Smita.KoralahalliChannabasappa@amd.com/