cpu/x86/mp_init.c: Keep track of initial lapic ID inside device_path

It's quite confusing to keep track of lapic ID inside the device
struct and initial lapic ID inside an array.

Change-Id: I4d9f8d23c0b0e5c142f6907593428d8509e4e7bb
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
---
M src/arch/x86/cpu.c
M src/arch/x86/include/arch/cpu.h
M src/cpu/x86/lapic/lapic_cpu_init.c
M src/cpu/x86/mp_init.c
M src/device/cpu_device.c
M src/include/cpu/cpu.h
M src/include/device/path.h
7 files changed, 54 insertions(+), 51 deletions(-)