nb/intel/i945: Use parallel MP init

Use the parallel mp init path to initialize AP's. This should result
in a moderate speedup.

Tested on Intel D945GCLF (1 core 2 threads), still boots fine and is
26ms faster compared to lapic_cpu_init.

This removes the option to disable HT siblings.

Change-Id: I955551b99e9cbc397f99c2a6bd355c6070390bcb
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/25600
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>

src/mainboard/getac/p470/cmos.layout

@@ -53,7 +53,6 @@ entries
 #399          1       r       0        unused
 
 # coreboot config options: cpu
-400          1       e       2        hyper_threading
 #401          7       r       0        unused
 
 # coreboot config options: southbridge