soc/amd/phoenix/chip: make FSP-S call conditional

Only call amd_fsp_silicon_init if PLATFORM_USES_FSP2_0 is selected in
Kconfig. I'm not 100% sure about the data_fabric_set_mmio_np call yet,
but since it doesn't depend on PLATFORM_USES_FSP2_0 to compile, I'll
look into that one later.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I2666f1ac0f0354146ffe005b3ce99484defda7a8
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80242
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Varshit Pandya <pandyavarshit@gmail.com>
Reviewed-by: Matt DeVillier <matt.devillier@amd.corp-partner.google.com>

src/soc/amd/phoenix/chip.c

@@ -39,7 +39,8 @@ static void soc_init(void *chip_info)
 {
 	default_dev_ops_root.write_acpi_tables = soc_acpi_write_tables;
 
-	amd_fsp_silicon_init();
+	if (CONFIG(PLATFORM_USES_FSP2_0))
+		amd_fsp_silicon_init();
 
 	data_fabric_set_mmio_np();