fix(realm): make PCIe tests default for testing

This patch moves the PCIe DOE test to the default realm world
testsuite.

Also fixes some build issues and hardens the PCIe functions.

Note that FVP_Base_RevC model needs to have the following
options enabled for the PCIe tests to work :

    -C pci.pcie_rc.ahci0.endpoint.doe_supported=1
    -C pci.pcie_rc.ahci0.endpoint.ide_supported=1


Change-Id: Icfd6b68799b0bacb44299c6a3cf99a3c425f833d
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
diff --git a/tftf/tests/tests-realm-payload.mk b/tftf/tests/tests-realm-payload.mk
index ae4b20a..4da8e3e 100644
--- a/tftf/tests/tests-realm-payload.mk
+++ b/tftf/tests/tests-realm-payload.mk
@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2021-2023, Arm Limited. All rights reserved.
+# Copyright (c) 2021-2024, Arm Limited. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -44,4 +44,16 @@
 	$(addprefix lib/extensions/fpu/,				\
 		fpu.c							\
 	)
+
+TESTS_SOURCES	+=				\
+	$(addprefix tftf/tests/doe_tests/,	\
+		doe_helpers.c			\
+		test_doe.c			\
+	)
+
+TESTS_SOURCES	+=		\
+	$(addprefix lib/pcie/,	\
+		pcie.c		\
+		pcie_doe.c	\
+	)
 endif