x86/mce: Set CR4.MCE last during init

x86/mce: Set CR4.MCE last during init

Set the CR4.MCE bit as the last step during init. This brings the MCA
init order closer to what is described in the x86 docs.

x86 docs:
  AMD		Intel
  		MCG_CTL
  MCA_CONFIG	MCG_EXT_CTL
  MCi_CTL	MCi_CTL
  MCG_CTL
  CR4.MCE	CR4.MCE

Current Linux:
  AMD		Intel
  CR4.MCE	CR4.MCE
  MCG_CTL	MCG_CTL
  MCA_CONFIG	MCG_EXT_CTL
  MCi_CTL	MCi_CTL

Updated Linux:
  AMD		Intel
  MCG_CTL	MCG_CTL
  MCA_CONFIG	MCG_EXT_CTL
  MCi_CTL	MCi_CTL
  CR4.MCE	CR4.MCE

The new init flow will match Intel's docs, but there will still be a
mismatch for AMD regarding MCG_CTL. However, there is no known issue with this
ordering, so leave it for now.

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