x86/msr: Add missing __percpu annotations

Sparse rightfully complains about using a plain pointer for per CPU
accessors:

  msr-smp.c:15:23: sparse: warning: incorrect type in initializer (different address spaces)
  msr-smp.c:15:23: sparse:    expected void const [noderef] __percpu *__vpp_verify
  msr-smp.c:15:23: sparse:    got struct msr *

Add __percpu annotations to the related datastructure and function
arguments to cure this. This also cures the related sparse warnings at the
callsites in drivers/edac/amd64_edac.c.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20240304005104.513181735@linutronix.de