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

commit 0bf87165 upstream

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

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


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>