feat(cert_create): define the cca chain of trust

Selection of the cca chain of trust is done through the COT build
option:

> make COT=cca

Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
Change-Id: I123c0a841f67434633a3123cc1fa3e2318585482
diff --git a/tools/cert_create/src/cca/cot.mk b/tools/cert_create/src/cca/cot.mk
new file mode 100644
index 0000000..d0c80bb
--- /dev/null
+++ b/tools/cert_create/src/cca/cot.mk
@@ -0,0 +1,10 @@
+#
+# Copyright (c) 2022, Arm Limited. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+PLAT_MSG		:=	Confidential Compute Architecture root of trust
+PLAT_INCLUDE		:=	../../include/tools_share
+
+OBJECTS += src/cca/cot.o