x86/microcode: Replace the all-in-one rendevous handler

mainline inclusion
from mainline-v6.7-rc1
commit 0bf871651211b58c7b19f40b746b646d5311e2ec
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I8XRMW


CVE: NA

--------------------------------

with a new handler which just separates the control flow of primary and
secondary CPUs.

Intel-SIG: commit 0bf871651211 x86/microcode: Replace the all-in-one rendevous handler.
Microcode restructuring backport.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231002115903.433704135@linutronix.de


[ Aubrey Li: amend commit log ]
Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com>