Core: Suppress handler mode logging

The logging in handler mode accesses the stdio driver, while
this stdio driver may be designed to be working in thread mode.
Suppress handler mode logging at current stage until the logging
mechanism is available.

Change-Id: I18a17c5a7f3cd6be23cce04fba3edeba81521deb
Signed-off-by: Ken Liu <ken.liu@arm.com>
21 files changed