x86/mce: Do 'UNKNOWN' vendor check early

x86/mce: Do 'UNKNOWN' vendor check early

The 'UNKNOWN' vendor check is handled as a quirk that is run on each
online CPU. However, all CPUs are expected to have the same vendor.

Move the 'UNKNOWN' vendor check to the BSP-only init so it is done early
and once. Remove the unnecessary return value from the quirks check.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/20250908-wip-mca-updates-v6-0-eef5d6c74b9c@amd.com