feat(tftf): introduce handler for synchronous exceptions

Introduce a handler for synchronous exceptions (for aarch64) which
currently is treated as unhandled exception.

Also, added the capability to allow registering a custom handler by tftf
framework to allow graceful exit while doing negative tests.

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: I4d8d1f5af9951edfe8f068ce85f7d434b2ec070f
diff --git a/include/lib/aarch64/sync.h b/include/lib/aarch64/sync.h
new file mode 100644
index 0000000..5058980
--- /dev/null
+++ b/include/lib/aarch64/sync.h
@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) 2022, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __SYNC_H__
+#define  __SYNC_H__
+
+typedef bool (*exception_handler_t)(void);
+void register_custom_sync_exception_handler(exception_handler_t handler);
+void unregister_custom_sync_exception_handler(void);
+
+#endif /* __SYNC_H__ */