cpu/x86/lapic: Drop SMM_SERIALIZED_INITIALIZATION

It was only evaluated on LEGACY_SMP_INIT path while model_106cx
has used PARALLEL_MP for a long time.

Change-Id: I90ce838f1041d55a7c77ca80e563e413ef3ff88d
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61479
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/cpu/intel/model_106cx/Kconfig

@@ -8,6 +8,5 @@ config CPU_INTEL_MODEL_106CX
 	select AP_IN_SIPI_WAIT
 	select TSC_SYNC_MFENCE
 	select SUPPORT_CPU_UCODE_IN_CBFS
-	select SERIALIZED_SMM_INITIALIZATION
 	select CPU_INTEL_COMMON
 	select CPU_INTEL_COMMON_TIMEBASE