Experimental: products: Disable multi-threading for all products

Created by: girishpathak

This change is a precursor to the subsequent changes where multi-threading support will be removed from the SCP firmware.

The change is inteded to allow platform owners to test respective platforms without multi-threading.

The term multi-threaded mode is misleading since it implies multiple threads of execution are concurrently supported (like in an OS), but that is not true. Also multi-threading add call overhead and could make things slower, and creates a larger memory footprint. Simply all of above is not needed at present, hence we expect multi-thread mode to be removed in near future from the firmware.

Change-Id: Ia5009ddf75a5f385ee8a8966e178900e462e6cf9 Signed-off-by: Girish Pathak girish.pathak@arm.com