soc/intel/xeon_sp: Introduce soc_cpu_is_enabled

Add a function to check if the CPU placed at the specified socket was
found usable during QPI init. This is useful for multi-socket
platforms were a CPU is missing or has been disabled due to an error.

Change-Id: I135968fcc905928b9bc6511e3ddbd7d12bad0096
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/76556
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/soc/intel/xeon_sp/spr/soc_acpi.c b/src/soc/intel/xeon_sp/spr/soc_acpi.c
index 5340b7b..2e77de2 100644
--- a/src/soc/intel/xeon_sp/spr/soc_acpi.c
+++ b/src/soc/intel/xeon_sp/spr/soc_acpi.c
@@ -394,7 +394,7 @@
 			const STACK_RES *ri =
 				&hob->PlatformData.IIO_resource[socket].StackRes[stack];
 
-			stack_enabled = hob->PlatformData.IIO_resource[socket].Valid &&
+			stack_enabled = soc_cpu_is_enabled(socket) &&
 					ri->Personality < TYPE_RESERVED;
 
 			printk(BIOS_DEBUG, "%s processing socket: %d, stack: %d, type: %d\n",