x86/CPU: Add a microcode loader callback

x86/CPU: Add a microcode loader callback

Add a callback function which the microcode loader calls when microcode
has been updated to a newer revision. Do the callback only when no error
was encountered during loading.

Tested-by: Ashok Raj <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Ashok Raj <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>