x86/MCE/AMD: Fix the thresholding machinery initialization order

Currently, the code sets up the thresholding interrupt vector and only
then goes about initializing the thresholding banks. Which is wrong,
because an early thresholding interrupt would cause a NULL pointer
dereference when accessing those banks and prevent the machine from
booting.

Therefore, set the thresholding interrupt vector only *after* having
initialized the banks successfully.

Fixes: 18807ddb7f88 ("x86/mce/AMD: Reset Threshold Limit after logging error")
Reported-by: Rafał Miłecki <[email protected]>
Reported-by: John Clemens <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Tested-by: Rafał Miłecki <[email protected]>
Tested-by: John Clemens <[email protected]>
Cc: Aravind Gopalakrishnan <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Tony Luck <[email protected]>
Cc: [email protected]
Cc: Yazen Ghannam <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=201291