Change in coreboot[master]: cpu/x86/lapic: Support switching to X2APIC mode

[Kyösti Mälkki (Code Review)]

Hello build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/55262

to look at the new patch set (#2).

Change subject: cpu/x86/lapic: Support switching to X2APIC mode
......................................................................

cpu/x86/lapic: Support switching to X2APIC mode

The options X2APIC_ONLY and X2APIC_RUNTIME were already user-visible
choices in menuconfig, but the functionality was not actually provided
except for platforms where FSP presumably enabled X2APIC.

Add the logic and related logging for switching to X2APIC operation.

TEST: qemu-system-x86_64 -M Q35 -accel kvm -bios coreboot.rom -serial stdio -smp 2

PARALLEL_MP, and either X2APIC_ONLY or X2APIC_RUNTIME, need to be selected
for the build of emulation/qemu-q35.

Change-Id: I19a990ba287d21ccddaa64601923f1c4830e95e9
Signed-off-by: Kyösti Mälkki 
---
M src/cpu/x86/lapic/lapic.c
M src/cpu/x86/mp_init.c
M src/include/cpu/x86/msr.h
3 files changed, 38 insertions(+), 10 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/62/55262/2