cpu/x86 mp_init: Add option for AMD INIT SIPI sequence

The common code adheres to the Intel requirement of bringing up the
cores with INIT SIPI SIPI.  This sequence is tolerated on some AMD
AMD CPUs but fails on others.  Add a way to skip the second SIPI.

TEST=Mock up on grunt and verify no errors
BUG=b:138919564

Change-Id: I201869003ddc7d04d332cd5734ac6d63979d89e0
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34759
Reviewed-by: Martin Roth <martinroth@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/cpu/x86/mp_init.c

@@ -482,6 +482,9 @@ static int start_aps(struct bus *cpu_bus, int ap_count, atomic_t *num_aps)
 	/* Wait for CPUs to check in up to 200 us. */
 	wait_for_aps(num_aps, ap_count, 200 /* us */, 15 /* us */);
 
+	if (CONFIG(X86_AMD_INIT_SIPI))
+		return 0;
+
 	/* Send 2nd SIPI */
 	if ((lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY)) {
 		printk(BIOS_DEBUG, "Waiting for ICR not to be busy...");