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/doe_tests/doe_helpers.h b/tftf/tests/doe_tests/doe_helpers.h
index 08137e3..d0fc5c8 100644
--- a/tftf/tests/doe_tests/doe_helpers.h
+++ b/tftf/tests/doe_tests/doe_helpers.h
@@ -8,6 +8,8 @@
 #ifndef DOE_HELPERS_H
 #define DOE_HELPERS_H
 
+#include <stdint.h>
+
 void pcie_init(void);
 int find_doe_device(uint32_t *bdf_ptr, uint32_t *cap_base_ptr);
 int doe_discovery(uint32_t bdf, uint32_t doe_cap_base);