Add log client component

Adding a client and a related factory component that will be used
by the SPs to use the logging SP.
Extending trace functions with the configurable option to log using
the logging SP. In case logging with the logging SP fails,
the FFA_CONSOLE_LOG mechanism will be used.

Signed-off-by: Gabor Toth <gabor.toth2@arm.com>
Signed-off-by: Gabor Ambrus <gabor.ambrus@arm.com>
Change-Id: I1c03d145faa8f27c3e5878de0f6d28bec23ca9af
8 files changed