soc/intel/xeon_sp: Remove duplicated Kconfig POSTCAR_STAGE

POSTCAR_STAGE is already selected in XEON_SP_COMMON_BASE

Change-Id: I3f94e6cc76c8f376119ffa8ec43fa1a43fb40977
Signed-off-by: Jincheng Li <jincheng.li@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82795
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>

src/soc/intel/xeon_sp/Kconfig

@@ -46,7 +46,6 @@ config XEON_SP_COMMON_BASE
 	select USE_FSP_NOTIFY_PHASE_POST_PCI_ENUM
 	select USE_FSP_NOTIFY_PHASE_READY_TO_BOOT
 	select USE_FSP_NOTIFY_PHASE_END_OF_FIRMWARE
-	select POSTCAR_STAGE
 
 if XEON_SP_COMMON_BASE