SPMC: Set secure tests control via UART

Signed-off-by: J-Alves <joao.alves@arm.com>
Change-Id: Iff3642bfd2841f572a522a9752c8ee2c5c011a12
diff --git a/BUILD.gn b/BUILD.gn
index 5aee6a9..026caee 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -71,6 +71,7 @@
     plat_psci = "//src/arch/aarch64/plat/psci:spmc"
     secure_world = "1"
     pl011_base_address = "0x1c090000"
+    hftest_ctrl = "//test/hftest:ctrl_uart"
   }
 }