x86/microcode/intel: Establish staging control logic

x86/microcode/intel: Establish staging control logic

When microcode staging is initiated, operations are carried out through
an MMIO interface. Each package has a unique interface specified by the
IA32_MCU_STAGING_MBOX_ADDR MSR, which maps to a set of 32-bit registers.

Prepare staging with the following steps:

  1.  Ensure the microcode image is 32-bit aligned to match the MMIO
      register size.

  2.  Identify each MMIO interface based on its per-package scope.

  3.  Invoke the staging function for each identified interface, which
      will be implemented separately.

  [ bp: Improve error logging. ]

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Anselm Busse <abusse@amazon.de>
Link: https://lore.kernel.org/all/871pznq229.ffs@tglx