arch/x86: Flip option NO_CAR_GLOBAL_MIGRATION

It is easier to track CAR_GLOBAL_MIGRATION which is
the approach to be deprecated with the next release.

This change enforces new policy; POSTCAR_STAGE=y is
not allowed together with CAR_GLOBAL_MIGRATION=y.

Change-Id: I0dbad6a14e68bf566ac0f151dc8ea259e5ae2250
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34804
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/icelake/Kconfig

@@ -32,7 +32,6 @@ config CPU_SPECIFIC_OPTIONS
 	select PARALLEL_MP_AP_WORK
 	select MICROCODE_BLOB_UNDISCLOSED
 	select PLATFORM_USES_FSP2_1
-	select POSTCAR_STAGE
 	select REG_SCRIPT
 	select SMP
 	select SOC_AHCI_PORT_IMPLEMENTED_INVERT