Configs for ENABLE_PIE=1 testing

Adding configs to test ENABLE_PIE=1 for BL31 with RESET_TO_BL31=0, TSP,
and BL2_AT_EL3.

Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
Change-Id: I82065281605dd441345b798948fcd6a1afa2103d
diff --git a/tf_config/fvp-default-pie b/tf_config/fvp-default-pie
new file mode 100644
index 0000000..b45bb2e
--- /dev/null
+++ b/tf_config/fvp-default-pie
@@ -0,0 +1,3 @@
+CROSS_COMPILE=aarch64-none-elf-
+PLAT=fvp
+ENABLE_PIE=1