rpi4: enable RPi4 PCI SMC conduit

Now that we have adjusted the address map, added the
SMC conduit code, and the RPi4 PCI callbacks, lets
add the flags to enable everything in the build.

By default this service is disabled because the
expectation is that its only useful in a UEFI+ACPI
environment.
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Change-Id: I2a3cac6d63ba8119d3b711db121185816b89f8a2

plat/rpi/rpi4/platform.mk

 #
-# Copyright (c) 2013-2019, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2013-2021, ARM Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -86,6 +86,9 @@ RPI3_RUNTIME_UART		:= 0
 # Use normal memory mapping for ROM, FIP, SRAM and DRAM
 RPI3_USE_UEFI_MAP		:= 0
 
+# SMCCC PCI support (should be enabled for ACPI builds)
+SMC_PCI_SUPPORT            	:= 0
+
 # Process platform flags
 # ----------------------
 
@@ -96,6 +99,7 @@ $(eval $(call add_define,RPI3_PRELOADED_DTB_BASE))
 endif
 $(eval $(call add_define,RPI3_RUNTIME_UART))
 $(eval $(call add_define,RPI3_USE_UEFI_MAP))
+$(eval $(call add_define,SMC_PCI_SUPPORT))
 
 ifeq (${ARCH},aarch32)
   $(error Error: AArch32 not supported on rpi4)
@@ -105,3 +109,8 @@ ifneq ($(ENABLE_STACK_PROTECTOR), 0)
 PLAT_BL_COMMON_SOURCES	+=	drivers/rpi3/rng/rpi3_rng.c		\
 				plat/rpi/common/rpi3_stack_protector.c
 endif
+
+ifeq ($(SMC_PCI_SUPPORT), 1)
+BL31_SOURCES            +=      plat/rpi/rpi4/rpi4_pci_svc.c
+endif
+