soc/amd/phoenix/Makefile: conditionally add fsp_[m,s]_params.c

fsp_m_params.c and fsp_s_params.c only contain FSP-specific code, so
only add those to the build if the SOC_AMD_PHOENIX_FSP Kconfig option is
selected. Other files have FSP-specific parts too, but those will be
reworked in future patches.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: Ife38ca6a548d7c3c2e765d9c9f30e0a4057bb373
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79984
Reviewed-by: Martin Roth <martin.roth@amd.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/phoenix/Makefile.inc

@@ -21,7 +21,7 @@ bootblock-y	+= espi_util.c
 
 verstage-y	+= espi_util.c
 
-romstage-y	+= fsp_m_params.c
+romstage-$(CONFIG_SOC_AMD_PHOENIX_FSP) += fsp_m_params.c
 romstage-y	+= romstage.c
 romstage-y	+= soc_util.c
 
@@ -30,7 +30,7 @@ ramstage-y	+= agesa_acpi.c
 ramstage-y	+= chip.c
 ramstage-y	+= cpu.c
 ramstage-y	+= fch.c
-ramstage-y	+= fsp_s_params.c
+ramstage-$(CONFIG_SOC_AMD_PHOENIX_FSP) += fsp_s_params.c
 ramstage-y	+= graphics.c
 ramstage-y	+= mca.c
 ramstage-y	+= root_complex.c