soc/intel/mp_init: Skip before_post_cpus_init if !USE_COREBOOT_MP_INIT

This patch ensures all APs finish the task and continue
before_post_cpus_init() if coreboot decides to perform multiprocessor
initialization using native coreboot drivers instead of using
FSP MP PPI implementation.

BUG=b:233199592
TEST=Build and boot google/kano to ChromeOS.

Signed-off-by: Subrata Banik <subratabanik@google.com>
Change-Id: I3b76974ab19323201bf1dca9af423481a40f65c9
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65173
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/common/block/cpu/mp_init.c

@@ -183,6 +183,16 @@ static void wrapper_init_core_prmrr(void *unused)
 
 void before_post_cpus_init(void)
 {
+	/*
+	 * Ensure all APs finish the task and continue if coreboot decides to
+	 * perform multiprocessor initialization using native coreboot drivers
+	 * instead using FSP MP PPI implementation.
+	 *
+	 * Ignore if USE_COREBOOT_MP_INIT is not enabled.
+	 */
+	if (!CONFIG(USE_COREBOOT_MP_INIT))
+		return;
+
 	if (mp_run_on_all_cpus(&wrapper_init_core_prmrr, NULL) != CB_SUCCESS)
 		printk(BIOS_ERR, "core PRMRR sync failure\n");